A062737 Primes p such that 4p-1 is also prime.

2, 3, 5, 11, 17, 41, 53, 71, 83, 131, 137, 173, 197, 227, 263, 281, 293, 383, 431, 467, 503, 521, 563, 587, 593, 617, 677, 683, 701, 743, 797, 827, 887, 911, 977, 983, 1013, 1061, 1091, 1151, 1163, 1181, 1277, 1307, 1361, 1481, 1511, 1523, 1553, 1607, 1613

Offset: 1

Author

Reiner Martin, Jul 12 2001

Keywords

• nonn
• easy

Comments

For n>1, 4*a(n) is a solution to the equation phi(x-1) - phi(x) = x/2. - Farideh Firoozbakht, Dec 17 2014

Links

• Harry J. Smith, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A005384, A007700, A005382.

Programs

Maple

select(n -> isprime(n) and isprime(4*n-1), [2,seq(2*k+1,k=1..1000)]); # Robert Israel, Dec 17 2014

PARI

{ n=0; forprime (p=2, 10^5, if (isprime(4*p - 1), write("b062737.txt", n++, " ", p); if (n==1000, break)) ) } \\ Harry J. Smith, Aug 10 2009