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 A202517 #9 Aug 19 2024 15:11:55
%S A202517 1,1,13,2299,4465027,83649932869,14413888012788031,
%T A202517 22412828378864422506133,312169717565869706933620630009,
%U A202517 38865154523992131836783382601539858727,43266472789023671032936589458127528396392744933
%N A202517 G.f.: exp( Sum_{n>=1} (3^n - 2^n)^n * x^n/n ).
%C A202517 More generally, for integers p and q, exp( Sum_{n>=1} (p^n - q^n)^n * x^n/n ) is a power series in x with integer coefficients.
%e A202517 G.f.: A(x) = 1 + x + 13*x^2 + 2299*x^3 + 4465027*x^4 + 83649932869*x^5 +...
%e A202517 where
%e A202517 log(A(x)) = (3-2)*x + (3^2 - 2^2)^2*x^2/2 + (3^3 - 2^3)^3*x^3/3 + (3^4 - 2^4)^4*x^4/4 + (3^5 - 2^5)^5*x^5/5 +...
%e A202517 more explicitly,
%e A202517 log(A(x)) = x + 5^2*x^2/2 + 19^3*x^3/3 + 65^4*x^4/4 + 211^5*x^5/5 +...
%o A202517 (PARI) {a(n)=polcoeff(exp(sum(m=1,n,(3^m-2^m)^m*x^m/m)+x*O(x^n)),n)}
%Y A202517 Cf. A202516, A155200, A155201, A155202.
%K A202517 nonn
%O A202517 0,3
%A A202517 _Paul D. Hanna_, Dec 20 2011