A322139 Number of labeled 2-connected simple graphs with n edges (the vertices are {1,2,...,k} for some k).

1, 1, 0, 1, 3, 18, 131, 1180, 12570, 154535, 2151439, 33431046, 573197723, 10743619285, 218447494812, 4787255999220, 112454930390211, 2818138438707516, 75031660452368001, 2114705500316025737, 62890323682634277951, 1967901134191778583146, 64623905086814216468839

Offset

0,5

Links

Andrew Howroyd, Table of n, a(n) for n = 0..100

Gus Wiseman, The a(6) = 131 labeled 2-connected graphs with 6 edges.

Formula

a(n) = Sum_{i=3..n} A123534(i, n). - Andrew Howroyd, Nov 30 2018

Prog

(PARI) seq(n)={Vec(1 + vecsum(Vec(serlaplace(log(x/serreverse(x*deriv(log(sum(k=0, n, (1 + y + O(y*y^n))^binomial(k, 2) * x^k / k!) + O(x*x^n)))))))))} \\ Andrew Howroyd, Nov 29 2018

Crossrefs

Cf. A002218, A013922, A123534, A275307, A291841, A304118, A304887, A322110, A322117, A322118, A322137, A322138.

Sequence in context: A362704 A047731 A291841 * A236342 A369012 A060909

Adjacent sequences: A322136 A322137 A322138 * A322140 A322141 A322142

Keyword

nonn

Author

Gus Wiseman, Nov 27 2018

Extensions

Terms a(7) and beyond from Andrew Howroyd, Nov 29 2018

Status

approved