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

0,4

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.

Prog

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

Crossrefs

The labeled version is A003030.

Row sums of A057276.

Column sums of A350753.

Cf. A003085, A049387, A350489, A350752.

Sequence in context: A368080 A348791 A250549 * A054953 A215172 A301811

Adjacent sequences: A035509 A035510 A035511 * A035513 A035514 A035515

Keyword

nonn,nice

Author

Ronald C. Read

Extensions

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

Status

approved