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%I #5 Mar 30 2012 18:39:23
%S 1,3,5,5,11,11,11,11,21,21,21,21,21,21,21,21,43,43,43,43,43,43,43,43,
%T 43,43,43,43,43,43,43,43,85,85,85,85,85,85,85,85,85,85,85,85,85,85,85,
%U 85,85,85,85,85,85,85,85,85,85,85,85,85,85,85,85,85,171,171,171,171,171
%N a(0)=1; for n > 0, a(n)=a(floor(n/2))+2*a(floor(n/4)).
%F n>0, a(n)=(1/3)*(8*2^(floor(log(n)/log(2)))+(-1)^(floor(log(n)/log(2))))
%o (PARI) a(n)=if(n<1,1,(1/3)*(8*2^(floor(log(n)/log(2)))+(-1)^(floor(log(n)/log(2)))))
%Y a(2^n) gives the Jacobsthal sequence A001045(n+3).
%Y Cf. A001045, A007731.
%K nonn
%O 0,2
%A _Benoit Cloitre_, Oct 23 2004
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