A181605 Twin primes ending in 7.

7, 17, 107, 137, 197, 227, 347, 617, 827, 857, 1277, 1427, 1487, 1607, 1667, 1697, 1787, 1877, 1997, 2027, 2087, 2237, 2267, 2657, 2687, 3167, 3257, 3467, 3527, 3557, 3767, 3917, 4127, 4157, 4217, 4337, 4517, 4547, 4637, 4787, 4967, 5417, 5477, 5657

Offset: 1

Author

Omar E. Pol, Nov 01 2010

Keywords

• nonn
• base

Comments

First disagrees with A092340 at n=26: A092340 contains 2707, but this sequence doesn't. Is this a subsequence of A092340? - Nathaniel Johnston, Jun 25 2011

Yes, it is a subsequence of A092340: see link. - Robert Israel, Apr 13 2021

Links

• Robert Israel, Table of n, a(n) for n = 1..10000
• Omar E. Pol, Determinacion geometrica de los numeros primos y perfectos
• Robert Israel, A181605 is a subsequence of A092340

Crossrefs

Cf. A001097, A092340, A181603, A181604, A181606.

Programs

Maple

[7, op(select(t -> isprime(t) and isprime(t+2), [seq(i,i=17..10000,30)]))]; # Robert Israel, Apr 13 2021

Mathematica

Select[Prime@ Range@ 800, Mod[ #, 10] == 7 && (PrimeQ[ # - 2] || PrimeQ[ # + 2]) &] (* Robert G. Wilson v, Nov 06 2010 *)

Formula

A001097 INTERSECT A030432. - R. J. Mathar, Nov 03 2010

Extensions

More terms from R. J. Mathar and Robert G. Wilson v, Nov 03 2010