A145097 a(n) is the largest proper divisor of the Mersenne composite A065341(n).

89, 178481, 2304167, 616318177, 164511353, 20408568497, 59862819377, 1416003655831, 3203431780337, 761838257287, 10334355636337793, 21514198099633918969, 224958284260258499201, 57912614113275649087721

Offset: 1

Author

Artur Jasinski, Oct 01 2008

Keywords

• nonn

Comments

Note that not all the largest divisors are primes.

Which divisors are prime? - see A145099. - Artur Jasinski, Oct 04 2008

Links

• Amiram Eldar, Table of n, a(n) for n = 1..183

Crossrefs

Cf. A065341, A135975, A135980, A136031.

Programs

Mathematica

a = {}; Do[m = 2^Prime[n] - 1; If[PrimeQ[m], null, AppendTo[a, Divisors[m][[ -2]]]], {n, 1, 40}]; a

Extensions

Name clarified by Amiram Eldar, Mar 12 2020