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A098025 p and 2p-1 are both Pythagorean primes, i.e., congruent to 1 (mod 4). 2
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified June 24 20:32 EDT 2022. Contains 354830 sequences. (Running on oeis4.)