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%I #8 Jun 06 2016 22:23:03
%S 1,16,1024,16384,4194304,67108864,4294967296,68719476736,
%T 70368744177664,1125899906842624,72057594037927936,
%U 1152921504606846976,295147905179352825856,4722366482869645213696,302231454903657293676544
%N Denominators of partial sums of a series for the inverse of the arithmetic-geometric mean (agM) of 1 and sqrt(3)/2.
%C See the references and the W. Lang link under A130035.
%C Also denominators of partial sums of a series for the inverse of the arithmetic-geometric mean (agM) of 1 and 1/2. For the numerators and the formula see A130037. Proof of the coincidence: The prefactor of each term of the sum (first formula in A130037) is binomial(2*n,n)^2, a natural number and 3 will never divide the even denominators.
%F a(n) = denom(sum((((2*j)!/(j!^2))^2)*(1/2^(6*j)),j=0..n)), n>=0.
%K nonn,frac,easy
%O 0,2
%A _Wolfdieter Lang_ Jun 01 2007
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