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A035080 Number of asymmetric connected graphs where every block is a complete graph. 3

%I #19 Feb 19 2016 05:51:11

%S 1,1,0,0,0,0,1,3,7,21,60,168,472,1344,3843,11104,32305,94734,279708,

%T 831401,2485877,7474667,22589771,68594611,209198103,640591332,

%U 1968920180,6072766832,18791062733,58321579888,181524367875,566488767763,1772261945866,5557515157647

%N Number of asymmetric connected graphs where every block is a complete graph.

%H Alois P. Heinz, <a href="/A035080/b035080.txt">Table of n, a(n) for n = 0..600</a>

%F G.f.: A(x) = B(x) + C(x) - B(x)*C(x), where B and C are g.f.s of A007561 and A035079, respectively.

%F a(n) ~ c * d^n / n^(5/2), where d = 3.38201646602027280742981874... (same as for A007561), c = 0.12430588691278777480105... . - _Vaclav Kotesovec_, Sep 10 2014

%p g:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,

%p add(binomial(b((i-1)$2), j)*g(n-i*j, i-1), j=0..n/i)))

%p end:

%p b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,

%p add(binomial(g(i$2), j)*b(n-i*j, i-1), j=0..n/i)))

%p end:

%p a:= n-> b((n-1)$2)+g(n$2)-add(b((i-1)$2)*g((n-i)$2), i=0..n):

%p seq(a(n), n=0..40); # _Alois P. Heinz_, May 20 2013

%t g[n_, i_] := g[n, i] = If[n==0, 1, If[i<1, 0, Sum[Binomial[b[i-1, i-1], j]*g[n-i*j, i-1], {j, 0, n/i}]]]; b[n_, i_] := b[n, i] = If[n==0, 1, If[i < 1, 0, Sum[Binomial[g[i, i], j]*b[n-i*j, i-1], {j, 0, n/i}]]]; a[n_] := b[n-1, n-1] + g[n, n] - Sum[b[i-1, i-1]*g[n-i, n-i], {i, 0, n}]; Table[ a[n], {n, 0, 40}] (* _Jean-François Alcover_, Feb 19 2016, after _Alois P. Heinz_ *)

%Y Cf. A007561, A035081.

%K nonn

%O 0,8

%A _Christian G. Bower_, Nov 15 1998

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Last modified April 25 01:35 EDT 2024. Contains 371964 sequences. (Running on oeis4.)