The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A050851 Numbers k such that 199*2^k-1 is prime. 0
 1, 5, 7, 15, 19, 23, 25, 27, 43, 65, 99, 125, 141, 165, 201, 211, 331, 369, 389, 445, 461, 463, 467, 513, 583, 835, 1071, 1085, 1107, 1187, 1197, 1491, 1513, 2505, 3859, 3941, 5989, 9693, 13125, 17009, 19459, 33147, 46433, 51091, 72813, 105169, 118531, 153127 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Table of n, a(n) for n=1..48. 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 Select[Range[1000], PrimeQ[199*2^# - 1] & ] (* Robert Price, Dec 29 2018 *) PROG (PARI) is(n)=ispseudoprime(199*2^n-1) \\ Charles R Greathouse IV, Jun 13 2017 CROSSREFS Sequence in context: A321130 A320381 A309292 * A058918 A079360 A314365 Adjacent sequences: A050848 A050849 A050850 * A050852 A050853 A050854 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(48) from the Wilfrid Keller link by Robert Price, Dec 29 2018 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified July 22 13:14 EDT 2024. Contains 374499 sequences. (Running on oeis4.)