A137530 Primes of the form 5k^2 + 1.

181, 1621, 6481, 8821, 35281, 52021, 58321, 87121, 103681, 112501, 131221, 141121, 151381, 172981, 184321, 302581, 380881, 414721, 450001, 486721, 544501, 626581, 691921, 737281, 784081, 808021, 1039681, 1067221, 1240021, 1300501, 1362421

Offset: 1

Author

Zak Seidov, Apr 27 2008

Keywords

• nonn

Comments

All k are multiples of 6, k=6j, where j are numbers in A138218.

Programs

Magma

[a: n in [0..1000]|IsPrime(a) where a is 1+5*n^2] // Vincenzo Librandi, Dec 13 2010

Mathematica

Select[5*Range[600]^2+1,PrimeQ] (* Harvey P. Dale, Dec 06 2015 *)