This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A339064 #5 Nov 22 2020 12:21:54
%S A339064 1,3,9,28,87,276,909,3086,10879,39821,151363,597062,2442044,10342904,
%T A339064 45301072,204895366,955661003,4590214994,22675644514,115068710553,
%U A339064 599149303234,3197694533771,17475917252052,97712883807625,558481251055893,3260409769087068
%N A339064 Number of unlabeled simple graphs with n edges rooted at two indistinguishable vertices.
%e A339064 The a(1) = 3 cases correspond to a single edge which can be attached to zero, one or both of the roots.
%o A339064 (PARI) \\ See A339063 for G.
%o A339064 seq(n)={my(A=O(x*x^n)); Vec((G(2*n, x+A, [1, 1]) + G(2*n, x+A, [2]))/2)}
%Y A339064 Cf. A000664, A053419 (one root), A303829, A339041, A339063, A339065.
%K A339064 nonn
%O A339064 0,2
%A A339064 _Andrew Howroyd_, Nov 22 2020