A342556 a(n) is the number of unlabeled connected graphs without endpoints with n edges.

1, 0, 0, 1, 1, 2, 5, 9, 22, 60, 164, 494, 1624, 5602, 20600, 79813, 323806, 1371025, 6034105, 27513424, 129641411, 629862824, 3149541908, 16183100922, 85328280263, 461123500894, 2551342936264, 14438734591483, 83506198920054, 493163726073210, 2971858162771887

Offset: 0

Author

Hugo Pfoertner, May 21 2021

Keywords

• nonn

Links

• Andrew Howroyd, Table of n, a(n) for n = 0..50
• Brendan McKay and Adolfo Piperno, Practical Graph Isomorphism, II, Journal of Symbolic Computation, 60 (2014), pp. 94-112.
• Brendan McKay and Adolfo Piperno, nauty and Traces, programs for computing automorphism groups of graphs and digraphs.

Crossrefs

Row sums of A342557.

Cf. A004108 (n vertices), A307317 (multigraph), A369290 (not necessarily connected).

Formula

Inverse Euler transform of A369290.

Extensions

a(0)=1 prepended and a(25) onwards from Andrew Howroyd, Feb 01 2024