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A032175 Number of connected functions of n points with no symmetries. 2


%S 1,1,2,4,9,18,42,91,208,470,1089,2509,5869,13730,32371,76510,181708,

%T 432635,1033656,2475384,5943395,14299532,34475030,83263872,201441431,

%U 488092897,1184353643,2877611984,7000359244,17049288304

%N Number of connected functions of n points with no symmetries.

%H Andrew Howroyd, <a href="/A032175/b032175.txt">Table of n, a(n) for n = 1..500</a>

%H C. G. Bower, <a href="/transforms2.html">Transforms (2)</a>

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

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

%o 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)}

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

%o seq(n)={Vec(CHK(IdTreeGf(n), n))} \\ _Andrew Howroyd_, Aug 31 2018

%Y Cf. A002861, A004111.

%K nonn

%O 1,3

%A _Christian G. Bower_

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Last modified May 26 04:46 EDT 2019. Contains 323579 sequences. (Running on oeis4.)