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 A135077 #2 Mar 30 2012 18:37:07
%S A135077 1,1,3,18,209,4650,198933,16482902,2663887921,844592892082,
%T A135077 527562202908045,651188478953301102,1591732149339598508105,
%U A135077 7716508793733513473433162,74274446413528969422741614565
%N A135077 E.g.f. A(x) = 1 + Sum_{n>=1} (1/n!)*Product_{k=0..n-1} [exp(2^k*x) - 1].
%e A135077 E.g.f.: A(x) = 1 + x + 3x^2/2! + 18x^3/3! + 209x^4/4! + 4650x^5/5! +...;
%e A135077 A(x) = 1 + [exp(x)-1] + [exp(x)-1][exp(2x)-1]/2! + [exp(x)-1][exp(2x)-1][exp(4x)-1]/3! + [exp(x)-1][exp(2x)-1][exp(4x)-1][exp(8x)-1]/4! +...
%o A135077 (PARI) {a(n)=n!*polcoeff(1+sum(j=1,n,(1/j!)*prod(k=0,j-1,1*exp(2^k*x)-1)),n)}
%Y A135077 Cf. variants: A001831, A135078.
%K A135077 nonn
%O A135077 0,3
%A A135077 _Paul D. Hanna_, Nov 24 2007