A321582 Primes p such that (4*p+1)/5 is prime.

241, 421, 541, 571, 751, 1171, 1291, 1621, 1861, 2011, 2221, 2251, 2341, 2521, 2671, 2851, 2971, 3271, 3361, 3391, 3541, 3571, 3691, 4021, 4201, 4591, 4621, 4861, 5641, 5701, 5821, 6211, 6961, 7321, 7351, 7591, 7951, 8101, 8161, 8191, 8221, 8821, 8971, 9151, 9241, 9421

Offset: 1

Author

David James Sycamore, Nov 13 2018

Keywords

• nonn

Comments

Subsequence of A320774.

Examples

			241 is a term since it is prime and (4*241+1)/5 = 193, prime.
		

Links

• Seiichi Manyama, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A320774.

Programs

Maple

for n from 4 to 1000 do
Y := ithprime(n);
Z := 4*Y+1;
K := (1/5)*Z;
if mod(Z, 5) = 0 and isprime(K) then print(Y);
end if:
end do:

Mathematica

Select[Prime[Range[1000]], PrimeQ[(4 # + 1)/5] &] (* Amiram Eldar, Nov 13 2018 *)

Extensions

More terms from Seiichi Manyama, Dec 24 2018