A248409 Least prime of the form x^2+13*n^2.

13, 53, 181, 233, 389, 757, 641, 857, 1069, 1301, 1609, 1873, 2213, 2549, 3121, 3329, 3761, 4261, 4729, 5209, 5737, 6301, 6977, 7489, 8161, 8837, 9733, 10193, 10937, 11701, 12497, 13313, 14173, 15053, 16069, 17137, 18121, 18773, 19777, 20809, 21997, 23053, 24137, 25169, 27109, 27509

Offset: 1

Author

Zak Seidov, Oct 06 2014

Keywords

• nonn

Comments

Subsequence of A033210 (Primes of the form x^2+13*y^2).

Examples

			a(1)=13 because the least prime of the form x^2+13*1^2 is 13 (at x=0).
a(100)=130121 because the least prime of the form x^2+13*100^2 is 130121 (at x=11).
a(200)=520361 because the least prime of the form x^2+13*200^2 is 520361 (at x=19).
		

Links

• Jens Kruse Andersen, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A033210, A106856, A247881, A248221.

Programs

PARI

a(n) = {x = 0; while (!isprime(p=x^2+13*n^2), x++); p;} \\ Michel Marcus, Oct 06 2014