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A032186 Shifts left 2 places under "CIJ" (necklace, indistinct, labeled) transform. 0
1, 1, 1, 2, 6, 27, 160, 1183, 10477, 108149, 1275024, 16903440, 248915119, 4031045212, 71202358081, 1362297883463, 28066342411395, 619474462826562, 14583353438928682, 364748466791800669 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..20.

FORMULA

E.g.f. A(x) satisfies differential equation A''(x)=log(1/(1-A(x)), A'(0)=1, A''(0)=1. [From Vladimir Kruchinin, Nov 18 2011]

a(n)=n!*b(n), b(n)=b(n-2)*(n-2)+sum(i=0..n-4, b(i+3)*(i+1)*(i+2)*(i+3)*b(n-3-i)))/(n*(n-1)*(n-2)) n>0, b(1)=1, b(2)=1/2. [From Vladimir Kruchinin, Nov 18 2011]

PROG

(Maxima)

a(n):=if n<3 then 1/n! else (a(n-2)*(n-2)+sum(a(i+3)*(i+1)*(i+2)*(i+3)*a(n-3-i), i, 0, n-4))/(n*(n-1)*(n-2));

makelist(n!*a(n), n, 1, 17); [From Vladimir Kruchinin, Nov 18 2011]

CROSSREFS

Sequence in context: A118192 A058133 A009308 * A122938 A234568 A231934

Adjacent sequences:  A032183 A032184 A032185 * A032187 A032188 A032189

KEYWORD

nonn,eigen

AUTHOR

Christian G. Bower

STATUS

approved

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Last modified February 19 11:04 EST 2018. Contains 299330 sequences. (Running on oeis4.)