A176164 - OEIS

%I #22 Sep 08 2022 08:45:52

%S 2,3,5,7,11,13,17,19,29,31,41,43,47,53,59,61,67,71,73,83,89,97,101,

%T 103,107,109,113,127,131,137,139,149,151,157,167,173,179,181,191,193,

%U 197,199,211,223,227,229,233,239,241,251,257,263,269,271,277,281,283,293

%N Primes p such that (p-2)/7 is not a prime number.

%C The old definition was "Start with the list of primes; accept 2 but remove the list of primes S(2); accept the next prime (3) but remove the list of primes S(3); repeat".

%C If p is a prime, S(p) denotes the list of primes {7p+2, 7(7p+2)+2, 7(7(7p+2)+2)+2, ...}, stopping as soon as we reach the first composite number.

%H Vincenzo Librandi, <a href="/A176164/b176164.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Prime[Range[70]],!PrimeQ[(#-2)/7]&]  (* _Harvey P. Dale_, Mar 17 2011 *)

%o (Magma) [p: p in PrimesUpTo(300)| not IsPrime((p-2)/7)]; // _Vincenzo Librandi_, Sep 12 2013

%Y Cf. A169647, A176162.

%K nonn,easy

%O 1,1

%A _Vincenzo Librandi_, Apr 10 2010

%E New definition from _Jon E. Schoenfield_, Jun 18 2010