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a(n) ~ 2^(n+e) with e = 2.9701632052178...
Table of n, a(n) for n=0..28.
G.f. prod(k>=0, (1+2x^2^k)/(1-2x^2^k)).
(PARI) a(n)=if(n<1, n<1, if(n%2==0, 2*a(n-1)+a(n/2), 2*a(n-1)+2*a((n-1)/2)))
Sequence in context: A138517 A001934 A004403 * A208903 A079769 A107035
Adjacent sequences: A084563 A084564 A084565 * A084567 A084568 A084569
Ralf Stephan, Jun 28 2003