A172367 Numbers k > 0 such that k+4 is a prime.

1, 3, 7, 9, 13, 15, 19, 25, 27, 33, 37, 39, 43, 49, 55, 57, 63, 67, 69, 75, 79, 85, 93, 97, 99, 103, 105, 109, 123, 127, 133, 135, 145, 147, 153, 159, 163, 169, 175, 177, 187, 189, 193, 195, 207, 219, 223, 225, 229, 235, 237, 247, 253, 259, 265, 267, 273, 277, 279

Offset: 1

Author

Juri-Stepan Gerasimov, Feb 01 2010

Keywords

• nonn
• easy

Comments

The subsequence of primes A023200 consists of the smallest primes p of cousin prime pairs (p, p+4), while the subsequence of nonprimes is A164384. - Bernard Schott, Oct 19 2021

Examples

			a(1) = 5 - 4 = 1, a(2) = 7 - 4 = 3.
		

Links

• Sameen Ahmed Khan, Table of n, a(n) for n = 1..10000
• Sameen Ahmed Khan, Primes in Geometric-Arithmetic Progression, arXiv:1203.2083v1 [math.NT], (Mar 09 2012).

Crossrefs

Union of A023200 and A164384.

Cf. A000040, A006093, A040976, A086801.

Programs

Mathematica

Table[Prime[n]-4,{n,3,53}] (* Charles R Greathouse IV, Mar 12 2012 *)

PARI

a(n)=prime(n+2)-4 \\ Charles R Greathouse IV, Mar 12 2012

Formula

a(n) = prime(n+2) - 4.