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%I #5 Mar 30 2012 18:39:12
%S 1,2,4,12,24,48,96,192,384,768,1536,4608,9216,18432,36864,73728,
%T 147456,294912,589824,1179648,2359296,4718592,9437184,28311552,
%U 56623104,113246208,226492416,452984832,905969664,1811939328,3623878656
%N a(1)=1, then a(n)=3*a(n-1) if n is already in the sequence, a(n)=2*a(n-1) otherwise.
%C Inspired by A079000. Cf. A064437.
%F a(n+1)=3*a(n) for n=3 n of the form 3*2^k - 1, k>=2 . a(n+1)=2*a(n) otherwise. Hence a(n)=3*(3/2)^floor((log(n/3))/log(2))*2^n.
%o (PARI) a(n)=3*(3/2)^floor((log(n)-log(3))/log(2))*2^n
%K nonn
%O 1,2
%A _Benoit Cloitre_, Feb 14 2003
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