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 A274654 #7 Jul 08 2016 17:47:56 %S A274654 1,2,32,128,4096,16384,131072,524288,33554432,134217728,1073741824, %T A274654 4294967296,68719476736,274877906944,2199023255552,8796093022208, %U A274654 1125899906842624,4503599627370496,36028797018963968,144115188075855872,2305843009213693952 %N A274654 Denominators of coefficients of z^n/n! for the expansion of Fricke's hypergeometric function F_1(1/2,1/2;z). %C A274654 The numerators are given in A274653, where one finds the definition of Fricke's F1(a,b;z) by a recurrence and references. %D A274654 See A274653. %F A274654 a(n) = denominator(r(n)), with the rationals (in lowest terms) defined by the recurrence %F A274654 r(n) = ((2*n-1)^2/(4*n))*r(n-1) + 2*c(n)/(n*(2*n-1)), n >= 1, r(0) = 0, with c(n) = ((2*n)!)^2 / (n!^3*2^(4*n)). %e A274654 See A274653. %Y A274654 Cf. A274653. %K A274654 nonn,easy,frac %O A274654 0,2 %A A274654 _Wolfdieter Lang_, Jul 07 2016