A114743 - OEIS

A114743

a(1) =4, a(2) = 6, a(n+1) = least composite number of the form k*(a(n-1)) - a(n), not included earlier.

%I #4 Dec 05 2013 19:57:14

%S 4,6,10,8,12,20,16,24,40,32,48,80,64,96,160,128,192,320,256,384,640,

%T 512,768,1280,1024,1536,2560,2048,3072,5120,4096,6144,10240,8192,

%U 12288,20480,16384,24576,40960,32768,49152,81920,65536,98304,163840,131072

%N a(1) =4, a(2) = 6, a(n+1) = least composite number of the form k*(a(n-1)) - a(n), not included earlier.

%C a(3n+1) = 2*a(3n-2)= 2^(n+2). a(3n+2) = 2*a(3n-1). = 3*2^(n+1). a(3n+3) = 2*a(3n). =5*2^(n).

%F a(n)=2*a(n-3). G.f.: -2*x*(2+3*x+5*x^2)/(-1+2*x^3). a(n)=2*A114744(n+1). [From _R. J. Mathar_, Jul 07 2009]

%K nonn

%O 1,1

%A _Amarnath Murthy_, Nov 15 2005

%E More terms from _R. J. Mathar_, Jul 07 2009