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A309996 Number of forests of rooted identity trees with 2n colored nodes using exactly n colors. 2
1, 1, 60, 10746, 4191916, 2894100710, 3128432924009, 4887094401176148, 10429904418286375276, 29174096160751011237987, 103602945849963939278211780, 455474137757927866858846385930, 2428879210633773939611859814825540, 15447942216555014401018067561180236424 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..188

FORMULA

a(n) = A256068(2n+1,n).

MAPLE

b:= proc(n, k) option remember; `if`(n<2, n, add(b(n-j, k)*add(b(d, k)

      *k*d*(-1)^(j/d+1), d=numtheory[divisors](j)), j=1..n-1)/(n-1))

    end:

a:= n-> add(b(2*n+1, n-i)*(-1)^i*binomial(n, i), i=0..n):

seq(a(n), n=0..15);

CROSSREFS

Cf. A256068.

Sequence in context: A146498 A003750 A001525 * A146513 A269883 A251991

Adjacent sequences:  A309993 A309994 A309995 * A309997 A309998 A309999

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Aug 26 2019

STATUS

approved

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Last modified January 28 13:14 EST 2020. Contains 331321 sequences. (Running on oeis4.)