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A255967 Odd numbers n that are neither of the form p + 2^k nor of the form p - 2^k with 2^k < n, and p prime. 5

%I

%S 1,1973,3181,3967,4889,5617,7747,7913,8363,8587,8923,11437,11993,

%T 12517,13285,13973,14101,14231,14489,16117,16769,16849,18391,18611,

%U 19583,19819,21289,21683,21701,21893,22147,22817,22949,23651,24943,25829,27197,27437

%N Odd numbers n that are neither of the form p + 2^k nor of the form p - 2^k with 2^k < n, and p prime.

%C Odd n such that for all 2^k < n the numbers n + 2^k and n - 2^k are composite.

%o (MAGMA) lst:=[]; for n in [1..27437 by 2] do t:=0; k:=0; while 2^k lt n do if IsPrime(n-2^k) or IsPrime(n+2^k) then t:=1; break; end if; k+:=1; end while; if IsZero(t) then Append(~lst, n); end if; end for; lst;

%Y Cf. A076335.

%Y Subsequence of A006285. Supersequence of A256163.

%Y A153352 gives the primes.

%K nonn

%O 1,2

%A _Arkadiusz Wesolowski_, Mar 12 2015

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Last modified August 20 05:25 EDT 2019. Contains 326139 sequences. (Running on oeis4.)