A006599 Numbers k such that 2^(2k+1) + 2^(k+1) + 1 is prime.
0, 1, 2, 5, 9, 14, 78, 81, 141, 189, 498, 5070, 7349, 38645, 42618, 53346
Offset: 1
References
- J. Brillhart et al., Factorizations of b^n +- 1. Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 2nd edition, 1985; and later supplements.
- N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
Links
- J. Brillhart et al., Factorizations of b^n +- 1, Contemporary Mathematics, Vol. 22, Amer. Math. Soc., Providence, RI, 3rd edition, 2002.
- S. S. Wagstaff, Jr., The Cunningham Project
Crossrefs
A108062 is essentially the same sequence.
Programs
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PARI
isok(n) = isprime(2^(2*n+1) + 2^(n+1) + 1); \\ Michel Marcus, Mar 28 2014
Formula
a(n) = A108062(n) - 1. - Michael S. Branicky, Jan 02 2025
Extensions
More terms from Rick L. Shepherd, Sep 07 2002
a(13) from Jeppe Stig Nielsen, Mar 28 2014
a(14)-a(16) from Michael S. Branicky, Jan 02 2025
Comments