A190359 - OEIS

%I #5 Mar 30 2012 18:35:55

%S 5,7,11,19,37,67,131,263,523,1031,2053,4099,8209,16421,32771,65539,

%T 131101,262147,524341,1048583,2097169,4194371,8388619,16777259,

%U 33554473,67108961,13417757,268435459

%N Largest prime factor of the least number having exactly two odd prime factors that differ by 2^n.

%C The least number having exactly two odd prime factors that differ by 2^n is  given by the sequence A190358.

%e a(5) = 37 because A190358(5) = 185 = 5 * 37 , and 37 is the largest prime divisor

%e   such that 37 - 5 = 32 = 2^5.

%p with(numtheory):for m from 1 to 30 do: k:=2^m:id:=0:for n from 1 to 900000000

%p   while(id=0) do: x:=factorset(n):n1:=nops(x):n2:=bigomega(n):if n1=2 and n2=2

%p   and x[2]=x[1]+k then id:=1:printf(`%d, `, x[2]):else fi:od:od:

%Y Cf. A190358.

%K nonn

%O 1,1

%A _Michel Lagneau_, May 09 2011