A336117 Primes of the form q*2^h + 1, where q is a Mersenne prime.

7, 13, 29, 97, 113, 193, 449, 509, 769, 7937, 12289, 114689, 520193, 786433, 7340033, 8388593, 33292289, 33550337, 469762049, 2130706433, 3221225473, 8588886017, 137438691329, 206158430209, 2199023254529, 6597069766657, 562948879679489, 7881299347898369, 9007182074871809

Offset: 1

Author

Antti Karttunen, Jul 09 2020

Keywords

• nonn

Crossrefs

Cf. A000265, A000668, A334092, A335874, A335885, A336116.

Programs

PARI

A000265(n) = (n>>valuation(n,2));
isA000668(n) = (isprime(n)&&!bitand(n,1+n));
isA336117(n) = (isprime(n)&&isA000668(A000265(n-1)));

Formula

For all n >= 1, A335885(a(n)) <= 2.

Extensions

More terms from Jinyuan Wang, Jul 11 2020