OFFSET
0,2
COMMENTS
a(n) ~ 2^(n+e) with e = 2.9701632052178...
FORMULA
G.f. prod(k>=0, (1+2x^2^k)/(1-2x^2^k)).
PROG
(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)))
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Ralf Stephan, Jun 28 2003
STATUS
approved