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

0,3

Links

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

Formula

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

Prog

(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

Crossrefs

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

Sequence in context: A272660 A193302 A289315 * A368076 A136393 A168370

Adjacent sequences: A102576 A102577 A102578 * A102580 A102581 A102582

Keyword

nonn

Author

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

Extensions

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

Status

approved