A046745 Number of connected graphs with <= n edges.

1, 2, 5, 10, 22, 52, 131, 358, 1068, 3390, 11461, 40964, 153786, 603927, 2471798, 10509270, 46296937, 210848414, 990794383, 4795761825, 23875074600, 122086530809, 640484152252, 3443478138871, 18954259427121, 106719731914780, 614115134054991, 3609008134177109

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• nice

Links

• Andrew Howroyd, Table of n, a(n) for n = 1..60
• G. A. Baker et al., High-temperature expansions for the spin-1/2 Heisenberg model, Phys. Rev., 164 (1967), 800-817.

Crossrefs

Partial sums of A002905.

Programs

Mathematica

A000664 = Cases[Import["https://oeis.org/A000664/b000664.txt", "Table"], {, }][[All, 2]];
(* EulerInvTransform is defined in A022562 *)
A002905 = EulerInvTransform[Rest@A000664];
Accumulate[A002905] (* Jean-François Alcover, Jul 16 2022 *)

Extensions

More terms from Vladeta Jovovic, Apr 10 2001

More terms from Vladeta Jovovic, Jul 05 2003

Terms a(25) and beyond added by Andrew Howroyd, May 06 2021