A102579 Number of n-node labeled digraphs whose underlying graphs are mating graphs, cf. A006024.

1, 1, 3, 36, 2160, 577260, 629332740, 2778611237640, 49231195558057800, 3472536190055702938560, 971496134741368475512176960, 1076456769176854177692230640971520, 4723714896453453856832035698858163891200, 82155195331101404797144020808246647196388279040

Offset: 0

Author

Goran Kilibarda, Zoran Maksimovic, Vladeta Jovovic, Jan 21 2005

Keywords

• nonn

Links

• Andrew Howroyd, Table of n, a(n) for n = 0..50

Crossrefs

Cf. A006024, A102580 (connected), A102596 (oriented), A102598, A369283.

Programs

PARI

\\ permcount, edges defined in A369283.
a(n) = {my(s=0); forpart(p=n, s += permcount(p)*(-1)^(n-#p)*edges(p, w->1 + 3^w)); s} \\ Andrew Howroyd, Jan 20 2024

Formula

a(n) = Sum_{k>=0} 3^k * A369283(n,k). - Andrew Howroyd, Jan 20 2024

Extensions

a(0)=1 prepended and a(12) onwards from Andrew Howroyd, Jan 20 2024