A098025 p and 2p-1 are both Pythagorean primes, i.e., congruent to 1 (mod 4).

37, 97, 157, 229, 337, 577, 601, 661, 829, 877, 937, 997, 1009, 1069, 1237, 1297, 1429, 1609, 1657, 2029, 2089, 2137, 2221, 2281, 2557, 2617, 3037, 3061, 3109, 3169, 3181, 3529, 3697, 3709, 3769, 3877, 4177, 4261, 4357, 4621, 4801, 4861, 4909, 5557, 5581

Offset

1,1

Comments

The product p*(2p-1) generates a family of base-2 pseudoprimes (i.e., a subsequence of A001567).

References

J.-M. De Koninck and A.Mercier, 1001 Problèmes en Théorie Classique Des Nombres, Problème 878 pp. 108; 353, Ellipses Paris 2004.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Mathematica

Select[ Prime[ Range[1000]], Mod[#, 4] == 1 && PrimeQ[2 #-1] && Mod[2 #-1, 4] == 1 & ] (* Jean-François Alcover, Sep 14 2011 *)

Crossrefs

Cf. A001567, A002144, A005382.

Sequence in context: A117854 A145480 A033222 * A256602 A142793 A139939

Adjacent sequences: A098022 A098023 A098024 * A098026 A098027 A098028

Keyword

nonn

Author

Lekraj Beedassy, Sep 10 2004

Extensions

More terms from Ray Chandler, Sep 16 2004

Status

approved