A050563 - OEIS

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A050563

Numbers k such that 75*2^k-1 is prime.

1

1, 3, 5, 6, 18, 19, 20, 22, 28, 29, 39, 43, 49, 75, 85, 92, 111, 126, 136, 159, 162, 237, 349, 381, 767, 969, 1247, 1893, 1951, 2363, 2657, 3065, 3090, 3836, 4110, 4342, 5671, 6807, 21945, 24658, 30082, 31811, 54510, 70828, 79292, 80938, 84432, 92235, 113429

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Robert Price, Table of n, a(n) for n = 1..60

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

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

Kosmaj, Riesel list k<300.

MATHEMATICA

Select[Range[1000], PrimeQ[75*2^# - 1] & ] (* Robert Price, Dec 22 2018 *)

PROG

(PARI) is(n)=ispseudoprime(75*2^n-1) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Sequence in context: A348658 A290761 A192119 * A282809 A168156 A295403

Adjacent sequences: A050560 A050561 A050562 * A050564 A050565 A050566

KEYWORD

hard,nonn

AUTHOR

N. J. A. Sloane, Dec 29 1999

EXTENSIONS

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

a(58)-a(60) from the Wilfrid Keller link by Robert Price, Dec 22 2018

STATUS

approved