1.
Exclamation mark
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The exclamation mark or exclamation point is a punctuation mark usually used after an interjection or exclamation to indicate strong feelings or high volume, and often marks the end of a sentence. Similarly, an exclamation mark is often used in warning signs. Other uses include, In mathematics it denotes the factorial operation, at the beginning of an expression to denote logical negation, e. g. A means the logical negation of A, also called not A. Graphically the exclamation mark is represented as a stop point with a vertical line above. One theory of its origin is that it is derived from a Latin exclamation of joy, the modern graphical representation is believed to have been born in the Middle Ages. Medieval copyists wrote the Latin word io at the end of a sentence to indicate joy, over time, the i moved above the o, and the o became smaller, becoming a point. The exclamation mark did not have its own dedicated key on standard manual typewriters before the 1970s, instead, one typed a period, backspaced, and typed an apostrophe. In the 1950s, secretarial dictation and typesetting manuals in America referred to the mark as bang, appeared in dialogue balloons to represent a gun being fired, although the nickname probably emerged from letterpress printing. This bang usage is behind the names of the interrobang, an unconventional character, and a shebang line. In the printing world, the mark can be called a screamer, a gasper. In hacker culture, the mark is called bang, shriek, or, in the British slang known as Commonwealth Hackish. For example, the password communicated in the spoken phrase Your password is em-nought-pee-aitch-pling-en-three is m0ph. n3, the exclamation mark is common to languages using the Latin alphabet, although usage varies slightly between languages. The exclamation mark was adopted in languages written in other scripts, such as Greek, Russian, Arabic, Hebrew, Chinese, Korean, Japanese and Devanagari. A sentence ending in an exclamation mark may be an exclamation, or an imperative, or may indicate astonishment or surprise, They were the footprints of a gigantic hound. Exclamation marks are occasionally placed mid-sentence with a similar to a comma, for dramatic effect, although this usage is obsolescent, On the walk. Informally, exclamation marks may be repeated for emphasis. The exclamation mark is used in conjunction with the question mark. This can be in protest or astonishment, a few writers replace this with a single, nonstandard punctuation mark, the interrobang, which is the combination of a question mark and an exclamation mark

2.
Double factorial
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In mathematics, the product of all the integers from 1 up to some non-negative integer n that have the same parity as n is called the double factorial or semifactorial of n and is denoted by n. = ∏ k =0 ⌈ n 2 ⌉ −1 = n ⋯ Therefore, = ∏ k =1 n 2 = n ⋯4 ⋅2, and for odd n it is n. = ∏ k =1 n +12 = n ⋯3 ⋅1, =9 ×7 ×5 ×3 ×1 =945. The double factorial should not be confused with the factorial function iterated twice, the sequence of double factorials for even n =0,2,4,6,8. Starts as 1,2,8,48,384,3840,46080,645120, the sequence of double factorials for odd n =1,3,5,7,9. Starts as 1,3,15,105,945,10395,135135, merserve states that the double factorial was originally introduced in order to simplify the expression of certain trigonometric integrals arising in the derivation of the Wallis product. Double factorials also arise in expressing the volume of a hypersphere, the term odd factorial is sometimes used for the double factorial of an odd number. For an even integer n = 2k, k ≥0. For odd n = 2k −1, k ≥1, in this expression, the first denominator equals. and cancels the unwanted even factors from the numerator. For an odd positive integer n = 2k −1, k ≥1, double factorials are motivated by the fact that they occur frequently in enumerative combinatorics and other settings. For instance, n. for odd values of n counts Perfect matchings of the complete graph Kn +1 for odd n. For instance, a graph with four vertices a, b, c. Perfect matchings may be described in several equivalent ways, including involutions without fixed points on a set of n +1 items or chord diagrams. Stirling permutations, permutations of the multiset of numbers 1,1,2,2, K, k in which each pair of equal numbers is separated only by larger numbers, where k = n + 1/2. From this recursive construction, a proof that the Stirling permutations are counted by the double permutations follows by induction, heap-ordered trees, trees with k +1 nodes labeled 0,1,2. K, such that the root of the tree has label 0, each node has a larger label than its parent. An Euler tour of the tree gives a Stirling permutation, unrooted binary trees with n + 5/2 labeled leaves. Each such tree may be formed from a tree with one leaf, by subdividing one of the n tree edges

3.
!!!
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. is a dance-punk band that formed in Sacramento, California, in 1996 by lead singer Nic Offer. Came from other bands such as The Yah Mos, Black Liquorice. They are currently based in New York City, Sacramento, and Portland, the bands sixth full-length album, As If, was released in October 2015. is an American band formed in the summer of 1995 by the merger of part of the group Black Liquorice and Popesmashers. After a successful joint tour, the two decided to mix the disco-funk with more aggressive sounds and integrate the hardcore singer Nic Offer from the Yah Mos. The bands name was inspired by the subtitles of the movie The Gods Must Be Crazy, however, as the bandmembers themselves say. Is pronounced by repeating thrice any monosyllabic sound, Chk Chk Chk is the most common pronunciation, and the URL of their official website and the title of their Myspace page suggest it is the preferred pronunciation. The bands full-length debut record out in 2000 as a self-titled album on the label Gold Standard Laboratories. A second full-length, Louden Up Now, was released on Touch and Go in America, released a new EP covering Take Ecstasy with Me by The Magnetic Fields, and Get Up by Nate Dogg. The following December, the drummer for the band, Mikel Gius, was struck. They released their album, Myth Takes in 2007. is composed of Mario Andreoni, Dan Gorman, Nic Offer, Tyler Pope. Touring members include Shannon Funchess and Paul Quattrone, the band also shared membership with the similar, defunct group Out Hud. Vocalist and drummer John Pugh officially left the band in July 2007 to concentrate on his new band Free Blood, Shannon Funchess stood in for Pugh during much of their 2007 tour. GSL26/LAB SERIES VOL.2 Live Live Live Take Ecstasy with Me/Get Up Yadnus Jamie, stereolad, a Stereolab cover band side project, containing the members of