A050586 Numbers n such that 121*2^n-1 is a prime.

1, 3, 21, 27, 37, 43, 91, 117, 141, 163, 373, 421, 1581, 2035, 10701, 18931, 21307, 51195, 64579, 156541, 302097, 334257, 368059, 383061, 410131, 494317, 541621, 990219, 1039965, 1526097, 1589157, 1695499, 1954243, 2033941

Offset

1,2

Comments

4553899 is also in the sequence. - Felix Fröhlich, Jul 04 2014

Links

Table of n, a(n) for n=1..34.

Author?, 12121 Search [Archived at Wayback Machine].

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.

PrimeGrid, Announcement of n=4553899 - Felix Fröhlich, Jul 04 2014

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

Mathematica

Select[Range[2500], PrimeQ[121*2^# - 1] &] (* Michael De Vlieger, Dec 10 2020 *)

Crossrefs

Cf. A032410.

Sequence in context: A067233 A007648 A273481 * A074217 A350247 A062219

Adjacent sequences: A050583 A050584 A050585 * A050587 A050588 A050589

Keyword

hard,nonn

Author

N. J. A. Sloane, Dec 29 1999

Extensions

More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 02 2008

Status

approved