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 A274656 #6 Jul 08 2016 17:47:43 %S A274656 1,2,64,768,98304,655360,10485760,293601280,30064771072,1082331758592, %T A274656 86586540687360,60473139527680,34832528367943680,362258295026614272, %U A274656 644014746713980928,2576058986855923712,5275768805080931762176,32613843522318487257088 %N A274656 Denominators of coefficients of z^n for the expansion of Fricke's hypergeometric function F_1(1/2,1/2;z). %C A274656 For the numerators see A274655. %C A274656 For the denominators of the coefficients of z^n/n! for the expansion of F_1(1/2,1/2;z) see A274654. %C A274656 See the main entry A274653 (with A274654) for the definition of Fricke's hypergeometric function F_1(a,b;z) with the recurrence and details on F_1(1/2,1/2;z). %D A274656 See A274653. %F A274656 a(n) = denominator(R(n)), where the rationals (in lowest terms) are R(n) = [z^n]F_1(1/2,1/2;z), and the recurrence for R(n) = r(n)/n! is obtained from the one given for r(n) in A274653. %F A274656 R(n) = ((2*n-1)/(2*n))^2*R(n-1) + 2*C(n)/(n*(2*n-1)), n >= 1, R(0) = 0, with C(n) = ((2*n)!)^2 / (n!^4*2^(4*n)). %e A274656 See A274653, A274654, A274655. %Y A274656 Cf. A274653. %K A274656 nonn,easy,frac %O A274656 0,2 %A A274656 _Wolfdieter Lang_, Jul 07 2016