A339044 Number of unlabeled connected simple graphs with n edges rooted at one oriented edge.

1, 2, 6, 18, 57, 188, 651, 2336, 8719, 33741, 135185, 559908, 2394326, 10557283, 47943126, 223987316, 1075455181, 5301593544, 26807904317, 138924912857, 737220195148, 4002876571636, 22221898966507, 126042573704637, 729944250603862, 4313430995825272

Offset

1,2

Links

Table of n, a(n) for n=1..26.

Formula

G.f.: x*f(x)/((1+x)*g(x)) where f(x) is the g.f. of A339063 and g(x) is the g.f. of A000664.

Prog

(PARI) \\ See A339063 for G.
seq(n)={my(A=O(x*x^n)); Vec(G(2*n, x+A, [1, 1])/G(2*n, x+A, [])/(1+x))}

Crossrefs

Cf. A000664, A002905, A303832, A304072, A339037, A339039, A339040, A339041, A339063.

Sequence in context: A104629 A000957 A307496 * A125305 A369621 A273203

Adjacent sequences: A339041 A339042 A339043 * A339045 A339046 A339047

Keyword

nonn

Author

Andrew Howroyd, Nov 21 2020

Status

approved