A094630 Number of 3-uniform T_0-covers on n vertices.

1, 0, 0, 0, 5, 893, 1039947, 34351783511, 72057317345649377, 19342812465159881755696499, 1329227995591486918148744122456237749, 46768052394574271874021714673583968385714779097997, 1684996666696914425950059618212919561731019777110516294609942096153

Offset

0,5

Links

Andrew Howroyd, Table of n, a(n) for n = 0..25

Formula

E.g.f.: exp(-x+x^2/2+x^3/3)*Sum_{n>=0} (2^binomial(n, 3)*exp(-2^(n-1)*x^2)*x^n/n!.

Prog

(PARI) seq(n)={Vec(serlaplace(exp(-x + x^2/2 + x^3/3 + O(x*x^n))*sum(k=0, n, 2^binomial(k, 3)*exp(-2^(k-1)*x^2 + O(x*x^(n-k)))*x^k/k!)))} \\ Andrew Howroyd, Jan 29 2020

Crossrefs

Cf. A094631, A059530, A060070.

Sequence in context: A299065 A299837 A299726 * A284637 A173914 A015940

Adjacent sequences: A094627 A094628 A094629 * A094631 A094632 A094633

Keyword

nonn

Author

Goran Kilibarda, Vladeta Jovovic, May 15 2004

Status

approved