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A032175 Number of connected functions of n points with no symmetries. 2
1, 1, 2, 4, 9, 18, 42, 91, 208, 470, 1089, 2509, 5869, 13730, 32371, 76510, 181708, 432635, 1033656, 2475384, 5943395, 14299532, 34475030, 83263872, 201441431, 488092897, 1184353643, 2877611984, 7000359244, 17049288304 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..500

C. G. Bower, Transforms (2)

FORMULA

"CHK" (necklace, identity, unlabeled) transform of A004111.

PROG

(PARI) \\ here IdTreeGf is g.f. of A004111.

IdTreeGf(N)={my(A=vector(N, j, 1)); for (n=1, N-1, A[n+1] = 1/n * sum(k=1, n, sumdiv(k, d, (-1)^(k/d+1) * d*A[d]) * A[n-k+1] ) ); x*Ser(A)}

CHK(p, n)={sum(d=1, n, moebius(d)/d*log(subst(1/(1+O(x*x^(n\d))-p), x, x^d)))}

seq(n)={Vec(CHK(IdTreeGf(n), n))} \\ Andrew Howroyd, Aug 31 2018

CROSSREFS

Cf. A002861, A004111.

Sequence in context: A026765 A264649 A259803 * A000678 A283877 A319567

Adjacent sequences:  A032172 A032173 A032174 * A032176 A032177 A032178

KEYWORD

nonn

AUTHOR

Christian G. Bower

STATUS

approved

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Last modified October 17 01:55 EDT 2018. Contains 316275 sequences. (Running on oeis4.)