A231383 Primes p such that p + 3*k is also prime, where p is k-th prime.

2, 7, 13, 19, 29, 37, 53, 71, 101, 107, 131, 139, 163, 173, 181, 199, 223, 229, 263, 281, 293, 311, 337, 397, 443, 463, 491, 557, 569, 659, 673, 719, 733, 787, 809, 827, 839, 857, 953, 983, 1013, 1069, 1091, 1109, 1151, 1223, 1249, 1283, 1307, 1451, 1493, 1549

Offset: 1

Author

K. D. Bajpai, Nov 08 2013

Keywords

• nonn

Examples

			a(5)= 29 which is 10th prime.  prime(10)+3*10= 29+30= 59 which is also prime.
a(7)= 53 which is 16th prime.  prime(16)+3*16= 53+48= 101 which is also prime.
		

Links

• K. D. Bajpai, Table of n, a(n) for n = 1..5100

Crossrefs

Cf. A061068 (primes: prime(m) plus its subscript).

Cf. A064402 (numbers n: prime(n)+n is prime).

Cf. A231232 (primes p : p+2*k is also prime).

Programs

Magma

[NthPrime(n): n in [1..250] | IsPrime(NthPrime(n)+3*n)]; // Vincenzo Librandi, Jan 19 2015

Maple

KD := proc() local a, b;  a:= ithprime(n); b:= a+3*n; if isprime(b) then RETURN (a); fi; end: seq(KD(), n=1..500);

Mathematica

KD = Select[Table[{Prime[n], Prime[n] + 3*n}, {n, 200}], PrimeQ[#[[2]]] &]; Transpose[KD][[1]]

PARI

is(n)=isprime(n) && isprime(n+3*primepi(n)) \\ Charles R Greathouse IV, Nov 08 2013