A007671 Numbers n such that 2^n + 2^((n + 1)/2) + 1 is prime. (Formerly M2481)

1, 3, 5, 11, 19, 29, 157, 163, 283, 379, 997, 10141, 14699, 77291, 85237, 106693, 203789, 3704053

Offset

1,2

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

Table of n, a(n) for n=1..18.

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

Prog

(PARI) for(n=1, 2000, if(n%2==1&&ispseudoprime(2^n+2^((n+1)/2)+1), print1(n, ", "))) \\ Charles R Greathouse IV, Feb 17 2017 edited by Aurelien Gibier Jun 29 2024.

Crossrefs

Cf. A057429.

Sequence in context: A048161 A284034 A051642 * A259589 A090471 A124098

Adjacent sequences: A007668 A007669 A007670 * A007672 A007673 A007674

Keyword

nonn,hard,more

Author

N. J. A. Sloane, Robert G. Wilson v

Extensions

More terms from Robert G. Wilson v, Sep 07 2000

203789 found and proved prime by Mike Oakes, on Sep 28 2000.

a(18) from Serge Batalov, Jun 16 2020

Status

approved