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, 2, 4, 12, 24, 48, 96, 192, 384, 768, 1536, 4608, 9216, 18432, 36864, 73728, 147456, 294912, 589824, 1179648, 2359296, 4718592, 9437184, 28311552, 56623104, 113246208, 226492416, 452984832, 905969664, 1811939328, 3623878656

Offset: 1

Author

Benoit Cloitre, Feb 14 2003

Keywords

• nonn

Comments

Inspired by A079000. Cf. A064437.

Programs

PARI

a(n)=3*(3/2)^floor((log(n)-log(3))/log(2))*2^n

Formula

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.