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Search: id:A132911
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A132911 a(n)=(n+1)(2n)!/2^n. +0
2
1, 2, 18, 360, 12600, 680400, 52390800, 5448643200, 735566832000, 125046361440000, 26134689540960000, 6585941764321920000, 1969196587532254080000, 689218805636288928000000 (list; graph; listen)
OFFSET

0,2

COMMENT

Define T(n,k)=((1+(-1)^n)/2)*C(k-1+n/2, n/2)*n!/2^(n/2). Then T(n,k) has e.g.f. 1/sum{j=0..k, C(k,j)*(-1)^j*x^(2j)/2^j}. T(n,1) is A000680 with interpolated zeros. T(n,3) is A132912.

FORMULA

E.g.f.: 1/(1-x^2+x^4/4) (with interpolated zeros);

CROSSREFS

Sequence in context: A087215 A090307 A123311 this_sequence A082402 A053916 A015203

Adjacent sequences: A132908 A132909 A132910 this_sequence A132912 A132913 A132914

KEYWORD

easy,nonn

AUTHOR

Paul Barry (pbarry(AT)wit.ie), Sep 04 2007

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Last modified July 26 13:41 EDT 2008. Contains 142293 sequences.


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