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A051685 Auxiliary sequence for calculation of number of even permutations of degree n and order exactly 4. 2
0, 0, 0, -6, -30, 0, 420, 2100, 6804, -20160, -376200, -2102760, -6606600, 53237184, 965306160, 5941244400, 12774059760, -305998041600, -5264368533216, -33983490935520, -16008359119200, 3139364813249280, 52132631033313600, 341037535726730304, -715693892444414400 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

REFERENCES

V. Jovovic, Some combinatorial characteristics of symmetric and alternating groups (in Russian), Belgrade, 1980, unpublished.

LINKS

Table of n, a(n) for n=1..25.

FORMULA

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.

CROSSREFS

Cf. A001189, A001473, A051684.

Sequence in context: A321141 A122802 A144746 * A165734 A260017 A123624

Adjacent sequences:  A051682 A051683 A051684 * A051686 A051687 A051688

KEYWORD

easy,sign

AUTHOR

Vladeta Jovovic

EXTENSIONS

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

STATUS

approved

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Last modified July 23 16:14 EDT 2019. Contains 325258 sequences. (Running on oeis4.)