A340028 Number of unlabeled 2-connected graphs with n vertices rooted at a pair of noninterchangeable vertices.

0, 1, 1, 7, 55, 655, 11147, 287791, 11787747, 804475261, 94875366649, 19825870580671, 7466490852631207, 5129453728126116131, 6487332587944013948099, 15213161506747424007012971, 66536415576917924594383104139, 545371527333985035460963541248785

Offset

1,4

Links

Andrew Howroyd, Table of n, a(n) for n = 1..30

Prog

(PARI) \\ See A004115 for graphsSeries and A339645 for combinatorial species functions.
cycleIndexSeries(n)={my(g=graphsSeries(n), gcr=sPoint(g)/g); x*sPoint(sSolve( sLog( gcr/(x*sv(1)) ), gcr ))}
{ my(N=15); Vec(OgfSeries(cycleIndexSeries(N)), -N) }

Crossrefs

Cf. A002218, A004115, A241768, A304070, A304074, A340029.

Sequence in context: A054910 A028562 A209668 * A365030 A180829 A227544

Adjacent sequences: A340025 A340026 A340027 * A340029 A340030 A340031

Keyword

nonn

Author

Andrew Howroyd, Jan 02 2021

Status

approved