A049387 Number of rooted unlabeled strongly connected digraphs with n nodes.

1, 1, 10, 287, 24427, 6222400, 4924590115, 12632686344657, 109225745061589342, 3281390460782419035867, 350135321051253376431022071, 134810599506208376766503740475912, 189491014587142646710566991248361106383, 981059614010249061197621212287544752507380541

Offset: 1

Author

Valery A. Liskovets

Keywords

• nonn

Comments

There is a rather difficult formula (simplified in 1973). The subsequent published value 6222928 for n=6 needs to be verified.

The correct value is 6222400. Terms up to a(7) have been confirmed by brute force using digraphs generated by nauty. - Andrew Howroyd, Jan 12 2022

Links

• Andrew Howroyd, Table of n, a(n) for n = 1..50
• V. A. Liskovets, The number of strongly connected directed graphs, Mat. Notes, 8 (1970), 877-882

Crossrefs

Cf. A035512, A350794.

Programs

PARI

\\ See PARI link in A350794 for program code.
A049387seq(15) \\ Andrew Howroyd, Jan 22 2022

Extensions

Terms a(6) and beyond from Andrew Howroyd, Jan 12 2022