A035512 Number of unlabeled strongly connected digraphs with n nodes.

1, 1, 1, 5, 83, 5048, 1047008, 705422362, 1580348371788, 12139024825260556, 328160951349343885604, 31831080872412589394328804, 11234274997368899732057135454531, 14576252633139820879894296847900227082

Offset: 0

Author

Ronald C. Read

Keywords

• nonn
• nice

References

• F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 218.
• V. A. Liskovets, A contribution to the enumeration of strongly connected digraphs, Dokl. AN BSSR, 17 (1973), 1077-1080, MR49#4849.
• R. C. Read and R. J. Wilson, An Atlas of Graphs, Oxford, 1998.
• R. W. Robinson, Numerical implementation of graph counting algorithms, AGRC Grant, Math. Dept., Univ. Newcastle, Australia, 1976.

Links

• Andrew Howroyd, Table of n, a(n) for n = 0..50 (terms 0..18 from R. W. Robinson)
• A. M. Hinz, S. Klavžar, U. Milutinović, C. Petr, The Tower of Hanoi - Myths and Maths, Birkhäuser 2013. See page 251. Book's website
• Eric Weisstein's World of Mathematics, Strongly Connected Digraph.

Crossrefs

The labeled version is A003030.

Row sums of A057276.

Column sums of A350753.

Cf. A003085, A049387, A350489, A350752.

Programs

PARI

\\ See PARI link in A350489 for program code.
A035512seq(15) \\ Andrew Howroyd, Jan 13 2022

Extensions

a(12) and a(13) added by N. J. A. Sloane from the Robinson report, Oct 17 2006