A177150 Numbers k such that k^2 + prime(k)^2 is a prime.

1, 2, 10, 20, 30, 34, 36, 50, 60, 100, 108, 110, 112, 114, 122, 130, 156, 188, 192, 198, 204, 208, 210, 216, 230, 234, 240, 246, 250, 260, 286, 290, 294, 300, 330, 332, 338, 342, 360, 388, 390, 392, 410, 416, 440, 460, 468, 484, 492, 502, 532, 542, 556, 570

Offset: 1

Author

Michel Lagneau, May 03 2010

Keywords

• nonn

Examples

			100 is in the sequence because the 100th prime is 541, and 100^2 + 541^2 = 302681 is prime.
		

Links

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

Crossrefs

Cf. A106587.

Programs

Magma

[m:m in [1..600] | IsPrime(m^2+NthPrime(m)^2)]; // Marius A. Burtea, Aug 11 2019

Maple

with(numtheory): nn:= 150: T:=array(1..nn):k:=1:for n from 1 to 1764 do:p:=ithprime(n):if type(p^2+n^2,prime)=true then T[k]:=n:k:=k+1: else fi:od:print(T):

Mathematica

Select[Range[600], PrimeQ[#^2 + Prime[#]^2] &] (* Amiram Eldar, Aug 11 2019 *)