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%I #14 Mar 12 2020 05:26:24
%S 89,178481,2304167,616318177,164511353,20408568497,59862819377,
%T 1416003655831,3203431780337,761838257287,10334355636337793,
%U 21514198099633918969,224958284260258499201,57912614113275649087721
%N a(n) is the largest proper divisor of the Mersenne composite A065341(n).
%C Note that not all the largest divisors are primes.
%C Which divisors are prime? - see A145099. - _Artur Jasinski_, Oct 04 2008
%H Amiram Eldar, <a href="/A145097/b145097.txt">Table of n, a(n) for n = 1..183</a>
%t a = {}; Do[m = 2^Prime[n] - 1; If[PrimeQ[m], null, AppendTo[a, Divisors[m][[ -2]]]], {n, 1, 40}]; a
%Y Cf. A065341, A135975, A135980, A136031.
%K nonn
%O 1,1
%A _Artur Jasinski_, Oct 01 2008
%E Name clarified by _Amiram Eldar_, Mar 12 2020