A337431 Numbers k such that the largest prime factor of 2^k - 1 is greater than the largest prime factor of 2^k + 1.

3, 5, 7, 9, 13, 14, 17, 19, 26, 27, 31, 33, 34, 35, 37, 46, 49, 51, 59, 61, 62, 65, 69, 74, 77, 78, 82, 83, 86, 89, 93, 97, 103, 107, 115, 118, 121, 122, 123, 127, 129, 130, 131, 133, 137, 141, 142, 143, 144, 145, 147, 150, 153, 154, 165, 166, 169, 170, 174, 175

Offset: 1

Author

Hugo Pfoertner, Sep 23 2020

Keywords

• nonn

Crossrefs

Cf. A002587, A005420, A337430 (complement).

Programs

PARI

for(n=2,175,my(p=vecmax(factor(2^n-1)[,1]),q=vecmax(factor(2^n+1)[,1]));if(p>q,print1(n,", ")))