cp's OEIS Frontend

A256237 Primes p such that for all 2^k < p the numbers p + 2^k, p - 2^k, p*2^k + 1, and p*2^k - 1 are composite.

%I A256237 #11 Sep 08 2022 08:46:11
%S A256237 8923,24943,35437,42533,52783,83437,105953,116437,126631,133241,
%T A256237 145589,164729,172331,192173,204013,215279,254329,304709,308899,
%U A256237 398833,430499,436687,454351,476869,479909,483443,497597,522479,527729,529103,545257,561439,562651
%N A256237 Primes p such that for all 2^k < p the numbers p + 2^k, p - 2^k, p*2^k + 1, and p*2^k - 1 are composite.
%o A256237 (Magma) lst:=[]; for p in [3..562651 by 2] do if IsPrime(p) then t:=0; k:=0; while 2^k lt p do if IsPrime(p-2^k) or IsPrime(p+2^k) or IsPrime(p*2^k-1) or IsPrime(p*2^k+1) then t:=1; break; end if; k+:=1; end while; if IsZero(t) then Append(~lst, p); end if; end if; end for; lst;
%Y A256237 Subsequence of A256163.
%Y A256237 Cf. A006285, A065381, A153352, A180247, A255967.
%K A256237 nonn
%O A256237 1,1
%A A256237 _Arkadiusz Wesolowski_, Mar 20 2015