A050541 - OEIS

A050541

Numbers k such that 31*2^k-1 is prime.

1, 5, 7, 11, 13, 23, 33, 35, 37, 47, 115, 205, 235, 271, 409, 739, 837, 887, 2189, 3465, 4653, 5073, 8011, 8061, 21957, 24589, 25657, 44653, 50321, 57647, 62083, 78179, 80021, 81655, 111667, 150265, 177089, 196433, 274115, 306751, 311389, 315523, 406105, 421129

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OFFSET

1,2

COMMENTS

773227 is also in the sequence. - Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008

LINKS

Table of n, a(n) for n=1..44.

Ray Ballinger and Wilfrid Keller, List of primes k.2^n + 1 for k < 300

Wilfrid Keller, List of primes k.2^n - 1 for k < 300

Kosmaj, Riesel list k<300.

Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime

MATHEMATICA