A172367 - OEIS

%I #32 Oct 21 2021 01:33:50

%S 1,3,7,9,13,15,19,25,27,33,37,39,43,49,55,57,63,67,69,75,79,85,93,97,

%T 99,103,105,109,123,127,133,135,145,147,153,159,163,169,175,177,187,

%U 189,193,195,207,219,223,225,229,235,237,247,253,259,265,267,273,277,279

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

%C 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

%H Sameen Ahmed Khan, <a href="/A172367/b172367.txt">Table of n, a(n) for n = 1..10000</a>

%H Sameen Ahmed Khan, <a href="http://arxiv.org/abs/1203.2083">Primes in Geometric-Arithmetic Progression</a>, arXiv:1203.2083v1 [math.NT], (Mar 09 2012).

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

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

%t Table[Prime[n]-4,{n,3,53}] (* _Charles R Greathouse IV_, Mar 12 2012 *)

%o (PARI) a(n)=prime(n+2)-4 \\ _Charles R Greathouse IV_, Mar 12 2012

%Y Union of A023200 and A164384.

%Y Cf. A000040, A006093, A040976, A086801.

%K nonn,easy

%O 1,2

%A _Juri-Stepan Gerasimov_, Feb 01 2010