cp's OEIS Frontend

A355485 Primes p such that neither g-1 nor g+1 is prime, where g is the gap from p to the next prime.

%I A355485 #11 Jul 13 2022 07:18:13
%S A355485 1327,2477,3137,5531,8467,9973,11213,11743,12011,12163,12347,14897,
%T A355485 16007,16493,16703,17257,19087,20297,20443,21433,24443,26267,26513,
%U A355485 29033,29501,29683,31193,31907,32653,32843,34549,34781,35543,35771,36161,36497,36947,37061,37747,38993,39581,40361,40433
%N A355485 Primes p such that neither g-1 nor g+1 is prime, where g is the gap from p to the next prime.
%C A355485 Primes prime(i) where A001223(i) is in A061673.
%H A355485 Robert Israel, <a href="/A355485/b355485.txt">Table of n, a(n) for n = 1..10000</a>
%e A355485 a(3) = 3137 is a term because 3137 is prime, the next prime is 3163 = 3137+26, and neither 26-1 = 25 nor 26+1 = 27 is prime.
%p A355485 q:= 2:
%p A355485 count:= 0:
%p A355485 R:= NULL:
%p A355485 while count < 100 do
%p A355485   p:= q;
%p A355485   q:= nextprime(q);
%p A355485   g:= q-p;
%p A355485   if not(isprime(g-1) or isprime(g+1)) then
%p A355485      count:= count+1;
%p A355485      R:= R, p
%p A355485   fi
%p A355485 od:
%p A355485 R;
%o A355485 (PARI) isok(p) = if (isprime(p), my(g=nextprime(p+1)-p); !isprime(g-1) && !isprime(g+1)); \\ _Michel Marcus_, Jul 05 2022
%Y A355485 Cf. A001223, A061673.
%K A355485 nonn
%O A355485 1,1
%A A355485 _J. M. Bergot_ and _Robert Israel_, Jul 04 2022