A320489 Number of connected nets on n unlabeled nodes.

1, 2, 6, 40, 581, 17954, 1376484, 275524246, 147627941386, 213261119287108, 836129127802137203, 8961301472286672235092, 264386586050074867407985650, 21609889100291959988235675761782, 4921292113269596022145447106163528469, 3138303995382684496665239674427115214538716

Offset: 0

Author

N. J. A. Sloane, Oct 25 2018

Keywords

• nonn

Links

• Andrew Howroyd, Table of n, a(n) for n = 0..50
• Edward A. Bender and E. Rodney Canfield, Enumeration of connected invariant graphs, Journal of Combinatorial Theory, Series B 34.3 (1983): 268-278. See p. 274.
• N. J. A. Sloane, Transforms

Crossrefs

Cf. A004103.

Formula

EULERi transform of A004103.

Extensions

a(0)=1 prepended by Andrew Howroyd, Jan 26 2020