A002258 Numbers k such that 15*2^k + 1 is prime.
1, 2, 4, 9, 10, 12, 27, 37, 38, 44, 48, 78, 112, 168, 229, 297, 339, 517, 522, 654, 900, 1518, 2808, 2875, 3128, 3888, 4410, 6804, 7050, 7392, 19219, 21445, 21550, 24105, 24995, 34224, 34260, 43388, 48444, 61758, 184290, 294894, 300488, 403929, 483098, 635989
Offset: 1
References
- H. Riesel, "Prime numbers and computer methods for factorization," Progress in Mathematics, Vol. 57, Birkhauser, Boston, 1985, Chap. 4, see pp. 381-384.
- N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
- N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
Links
- Jeppe Stig Nielsen, Table of n, a(n) for n = 1..63
- Ray Ballinger, Proth Search Page
- Ray Ballinger and Wilfrid Keller, List of primes k.2^n + 1 for k < 300
- Y. Gallot, Proth.exe: Windows Program for Finding Large Primes
- Wilfrid Keller, List of primes k.2^n - 1 for k < 300
- R. M. Robinson, A report on primes of the form k.2^n+1 and on factors of Fermat numbers, Proc. Amer. Math. Soc., 9 (1958), 673-681.
- Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime
Programs
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Mathematica
Select[Range[1000], PrimeQ[15*2^#+1] &] (* Amiram Eldar, Dec 12 2018 *)
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PARI
for(n=1, 10^10, if(ispseudoprime(15<
Extensions
Added more terms (from http://web.archive.org/web/20161028080239/http://www.prothsearch.net/riesel.html), Joerg Arndt, Apr 07 2013
a(57)-a(60) from http://www.prothsearch.com/riesel1.html by Robert Price, Dec 12 2018
Terms moved from Data to b-file, and one new term put in b-file, by Jeppe Stig Nielsen, Oct 16 2019