A339064 Number of unlabeled simple graphs with n edges rooted at two indistinguishable vertices.

1, 3, 9, 28, 87, 276, 909, 3086, 10879, 39821, 151363, 597062, 2442044, 10342904, 45301072, 204895366, 955661003, 4590214994, 22675644514, 115068710553, 599149303234, 3197694533771, 17475917252052, 97712883807625, 558481251055893, 3260409769087068

Offset: 0

Author

Andrew Howroyd, Nov 22 2020

Keywords

• nonn

Examples

			The a(1) = 3 cases correspond to a single edge which can be attached to zero, one or both of the roots.
		

Crossrefs

Cf. A000664, A053419 (one root), A303829, A339041, A339063, A339065.

Programs

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, [2]))/2)}