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%I #4 Apr 21 2020 19:07:24
%S 1,1,2,4,8,8,16,64,128,64,256,512,1024,2048,2048,16384,32768,16384,
%T 65536,131072,262144,262144,524288,2097152,4194304,2097152,8388608,
%U 8388608,16777216,134217728,67108864,1073741824,2147483648,1073741824,4294967296
%N Denominators of power series coefficients of A(x) satisfying A(A(x)) = x + Sum_{k>=2} prime(k-1) * x^k.
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Functional_square_root">Functional square root</a>
%e 1, 1, 1/2, 3/4, -3/8, 11/8, -47/16, 291/64, -361/128, -327/64, 2651/256, 8117/512, -23761/1024, -920509/2048, ...
%Y Cf. A008578, A030275, A030278, A334283 (numerators).
%K nonn,frac
%O 1,3
%A _Ilya Gutkovskiy_, Apr 21 2020