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A051685 Auxiliary sequence for calculation of number of even permutations of degree n and order exactly 4. 2

%I #6 Jun 13 2013 14:50:47

%S 0,0,0,-6,-30,0,420,2100,6804,-20160,-376200,-2102760,-6606600,

%T 53237184,965306160,5941244400,12774059760,-305998041600,

%U -5264368533216,-33983490935520,-16008359119200,3139364813249280,52132631033313600,341037535726730304,-715693892444414400

%N Auxiliary sequence for calculation of number of even permutations of degree n and order exactly 4.

%D V. Jovovic, Some combinatorial characteristics of symmetric and alternating groups (in Russian), Belgrade, 1980, unpublished.

%F a(n) = c(n, 4), where c(n, d)=Sum_{k=1..n} (-1)^(k+1)*(n-1)!/(n-k)! *Sum_{l:lcm{k, l}=d} c(n-k, l), c(0, 1)=1.

%Y Cf. A001189, A001473, A051684.

%K easy,sign

%O 1,4

%A _Vladeta Jovovic_

%E More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 05 2003

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Last modified March 29 09:44 EDT 2024. Contains 371268 sequences. (Running on oeis4.)