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Search: id:A024167
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| A024167 |
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n!(1 - 1/2 + 1/3 - .. + c/n), where c = (-1)^(n+1). |
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+0 15
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| 1, 1, 5, 14, 94, 444, 3828, 25584, 270576, 2342880, 29400480, 312888960, 4546558080, 57424792320, 948550176000, 13869128448000, 256697973504000, 4264876094976000, 87435019510272000, 1627055289796608000
(list; graph; listen)
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OFFSET
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1,3
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COMMENT
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Stirling transform of (-1)^n*a(n-1)=[0,1,-1,5,-14,94,...] is A000629(n-2)=[0,1,2,6,26,...]. - Michael Somos Mar 04 2004
Stirling transform of a(n)=[1,1,5,14,94,...] is A052882(n)=[1,2,9,52,375,...]. - Michael Somos Mar 04 2004
a(n) is the number of n-permutations that have a cycle with length greater than n/2. [From Geoffrey Critzer (critzer.geoffrey(AT)usd443.org), May 28 2009]
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FORMULA
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E.g.f.: ln(1+x)/(1-x). - Vladeta Jovovic (vladeta(AT)eunet.rs), Aug 25 2002
a(n)=a(n-1)+a(n-2)*(n-1)^2, n>1. - Michael Somos, Oct 29, 2002
b(n) = n! satisfies the above recurrence with b(1) = 1, b(2) = 2. This gives the finite continued fraction expansion a(n)/n! = 1/(1+1^2/(1+2^2/(1+3^2/(1+...+(n-1)^2/1)))). Cf. A142979. - Peter Bala (pbala(AT)toucansurf.com), Jul 17 2008
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PROGRAM
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(PARI) a(n)=if(n<0, 0, n!*polcoeff(log(1+x+x*O(x^n))/(1-x), n))
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CROSSREFS
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Cf. A000254.
Cf. A142979.
Sequence in context: A166795 A128102 A007838 this_sequence A077262 A058072 A027304
Adjacent sequences: A024164 A024165 A024166 this_sequence A024168 A024169 A024170
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KEYWORD
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nonn,easy
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AUTHOR
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Clark Kimberling (ck6(AT)evansville.edu)
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EXTENSIONS
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More terms from Benoit Cloitre (benoit7848c(AT)orange.fr), Jan 27 2002
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