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 A208056 #7 Apr 24 2012 23:57:26
%S A208056 1,2,18,10450,215011842,168283323489554,4613762736903044410402,
%T A208056 4429409381416783893511092430530,
%U A208056 147401742703370819998531165821635082467298,169293247178836261713452084817353169649400098579929282
%N A208056 G.f.: exp( Sum_{n>=1} 2*Pell(n)^(2*n) * x^n/n ), where Pell(n) = A000129(n).
%C A208056 Given g.f. A(x), note that A(x)^(1/2) does not yield an integer series.
%e A208056 G.f.: A(x) = 1 + 2*x + 18*x^2 + 10450*x^3 + 215011842*x^4 +...
%e A208056 such that, by definition,
%e A208056 log(A(x))/2 = x + 2^4*x^2/2 + 5^6*x^3/3 + 12^8*x^4/4 + 29^10*x^5/5 + 70^12*x^6/6 + 169^14*x^7/7 +...+ Pell(n)^(2*n)*x^n/n +...
%o A208056 (PARI) {Pell(n)=polcoeff(x/(1-2*x-x^2 +x*O(x^n)),n)}
%o A208056 {a(n)=polcoeff(exp(sum(m=1,n,2*Pell(m)^(2*m)*x^m/m) +x*O(x^n)),n)}
%o A208056 for(n=0,15,print1(a(n),", "))
%Y A208056 Cf. A000129, A211891, A208034, A208055, A204061, A204062.
%K A208056 nonn
%O A208056 0,2
%A A208056 _Paul D. Hanna_, Feb 22 2012