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A079352 a(1)=1, then a(n)=3*a(n-1) if n is already in the sequence, a(n)=2*a(n-1) otherwise. 1

%I

%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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Last modified October 15 13:38 EDT 2019. Contains 328030 sequences. (Running on oeis4.)