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%I #13 May 30 2020 05:06:26
%S 4,12,480,2880,171360,15079680,2979744768,256258050048,
%T 2206253681888256,32081134788337130496,3025251010540191405772800,
%U 60806680954426264344203059200,22247876027117358528051602802320179200
%N Denominator of G(n)=sum(k=1,n,1/2^k/2*sum(j=0,k-1,1/binomial(2^(k-j)+j,j))).
%D David H. Bailey and Richard E. Crandall, Random Generators and Normal Numbers, 2000.
%H M. Beeler, R. W. Gosper and R. Schroeppel, <a href="https://dspace.mit.edu/handle/1721.1/6086">HAKMEM</a>, Cambridge, MA: MIT Artificial Intelligence Laboratory, Memo AIM-239, Feb. 1972, Item 120, page 55. Also <a href="http://www.inwap.com/pdp10/hbaker/hakmem/series.html#item120">HTML transcription</a>.
%F lim n-->oo G(n) = Gamma constant = 0.5772....
%o (PARI) a(n)=denominator(sum(k=1,n,1/2^k/2*sum(j=0,k-1,1/binomial(2^(k-j)+j,j))))
%Y Cf. A085115 (numerators).
%K frac,nonn
%O 0,1
%A _Benoit Cloitre_, Aug 10 2003