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

0,6

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.

Formula

Inverse Euler transform of A369290.

Crossrefs

Row sums of A342557.

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

Sequence in context: A052962 A173565 A268651 * A002935 A128266 A088356

Adjacent sequences: A342553 A342554 A342555 * A342557 A342558 A342559

Keyword

nonn

Author

Hugo Pfoertner, May 21 2021

Extensions

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

Status

approved