A260554 Primes p such that p = q^2 + 4*r^2 where q and r are also primes.

41, 61, 109, 137, 149, 157, 269, 317, 389, 397, 461, 509, 557, 653, 701, 773, 797, 857, 877, 941, 977, 997, 1013, 1061, 1181, 1277, 1453, 1493, 1613, 1637, 1697, 1733, 1877, 1949, 1973, 1997, 2141, 2237, 2309, 2333, 2357, 2477, 2693, 2837, 2909, 2957, 3373

Offset

1,1

Links

Colin Barker, Table of n, a(n) for n = 1..1400

Example

149 is in the sequence because 149 = 7^2 + 4*5^2 and 149, 7 and 5 are all primes.

Mathematica

Select[#1^2 + 4 #2^2 & @@ # & /@ Tuples[Prime@ Range@ 60, 2], PrimeQ] // Sort (* Michael De Vlieger, Jul 29 2015 *)

Crossrefs

Cf. A260553, A260555, A260556, A260557.

Sequence in context: A141881 A139952 A195573 * A031415 A325072 A089345

Adjacent sequences: A260551 A260552 A260553 * A260555 A260556 A260557

Keyword

nonn

Author

Colin Barker, Jul 29 2015

Status

approved