A181605 - OEIS

%I #15 Apr 14 2021 05:21:51

%S 7,17,107,137,197,227,347,617,827,857,1277,1427,1487,1607,1667,1697,

%T 1787,1877,1997,2027,2087,2237,2267,2657,2687,3167,3257,3467,3527,

%U 3557,3767,3917,4127,4157,4217,4337,4517,4547,4637,4787,4967,5417,5477,5657

%N Twin primes ending in 7.

%C 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

%C Yes, it is a subsequence of A092340: see link. - _Robert Israel_, Apr 13 2021

%H Robert Israel, <a href="/A181605/b181605.txt">Table of n, a(n) for n = 1..10000</a>

%H Omar E. Pol, <a href="http://www.polprimos.com">Determinacion geometrica de los numeros primos y perfectos</a>

%H Robert Israel, <a href="/A181605/a181605.pdf">A181605 is a subsequence of A092340</a>

%F A001097 INTERSECT A030432. - _R. J. Mathar_, Nov 03 2010

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

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

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

%K nonn,base

%O 1,1

%A _Omar E. Pol_, Nov 01 2010

%E More terms from _R. J. Mathar_ and _Robert G. Wilson v_, Nov 03 2010