A145099 - OEIS

%I #11 Mar 12 2020 05:26:48

%S 1,1,0,1,1,0,0,0,1,1,0,0,0,1,1,1,1,1,0,1,1,1,1,0,0,0,1,0,0,0,0,0,1,1,

%T 0,0,1,0,0,0,1,0,0,0,1,1,0,1,0,1,0,0,0,0,0,0,1,0,0,0,0,1,1,0,0,0,0,0,

%U 0,1,0,0,0,0,0,1,0,0,0,0,1,0,0,0,0,1,0

%N a(n) = 1 if the largest proper divisor of Mersenne composite A145097(n) is prime and a(n) = 0 in opposite case.

%H Amiram Eldar, <a href="/A145099/b145099.txt">Table of n, a(n) for n = 1..191</a>

%t a = {}; Do[m = 2^Prime[n] - 1; k = Divisors[m][[ -2]]; If[PrimeQ[m], null, If[PrimeQ[k], AppendTo[a, 1], AppendTo[a, 0]]], {n, 1, 50}]; a

%Y Cf. A065341, A135975, A135980, A145097, A136031.

%K nonn

%O 1,1

%A _Artur Jasinski_, Oct 01 2008

%E Name clarified and more terms added by _Amiram Eldar_, Mar 12 2020