A075853 G.f. satisfies A(x) = 1 + x (1+Sum_{n=0..inf} [xA(x)]^(2^n)).
1, 1, 1, 2, 3, 6, 13, 27, 59, 131, 295, 684, 1609, 3829, 9203, 22262, 54179, 132565, 325823, 804108, 1991729, 4949794, 12339483, 30851429, 77347913, 194422788, 489892473, 1237207811, 3131186993, 7940340037, 20173254851, 51341234278
Offset: 0
Keywords
Programs
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PARI
a(n)=local(A,m); if(n<3,n>=0,A=1+x*O(x^n); m=1+ceil(log(n)/log(2)); for(k=1,n,A*=x; A=1+x*sum(i=0,m,A^2^i,1)); polcoeff(A,n))
Extensions
Definition corrected by Michael Somos, Oct 29 2002