A339040 - OEIS

%I #12 Dec 02 2020 17:50:17

%S 1,3,10,35,125,460,1747,6830,27502,113987,485971,2129956,9591009,

%T 44341610,210345962,1023182861,5100235807,26035673051,136023990102,

%U 726877123975,3970461069738,22156281667277,126234185382902,733899631974167,4351500789211840

%N Number of unlabeled connected simple graphs with n edges rooted at two noninterchangeable vertices.

%F G.f.: f(x)/g(x) - r(x)^2 where f(x), g(x) and r(x) are the g.f.'s of A339063, A000664 and A339039.

%o (PARI) \\ See A339063 for G.

%o seq(n)={my(A=O(x*x^n), g=G(2*n, x+A, [])); Vec(G(2*n, x+A, [1, 1])/g - (G(2*n, x+A, [1])/g)^2)}

%Y Cf. A000664, A002905, A303832, A304074, A339039, A339041, A339042, A339044, A339063.

%K nonn

%O 1,2

%A _Andrew Howroyd_, Nov 20 2020