A086931 - OEIS

%I #3 Mar 30 2012 18:50:37

%S 1,1,2,3,4,5,8,7,16,24,32,11,64,13,128,192,256,17,512,19,1024,1536,

%T 2048,23,4096,5120,8192,12288,16384,29,32768,31,65536,98304,131072,

%U 163840,262144,37,524288,786432,1048576,41,2097152,43,4194304,6291456

%N a(0) = 1, a(n) = spf(n)*a(n-spf(n)), where spf=A020639 (smallest prime factor).

%C a(n)=n iff n=1 or n=4 or n is prime: see A046022;

%C a(2*n)=2^n.

%K nonn

%O 0,3

%A _Reinhard Zumkeller_, Sep 21 2003