A118958 - OEIS

A118958

Primes that cannot be written as 2^k + p with p prime < 2^k.

2, 3, 5, 17, 31, 41, 47, 53, 59, 73, 79, 89, 97, 103, 109, 113, 127, 137, 149, 163, 167, 173, 179, 191, 193, 197, 223, 227, 233, 239, 251, 257, 271, 277, 281, 283, 307, 311, 313, 331, 337, 347, 349, 367, 373, 379, 389, 397, 401, 409, 421, 431, 433, 439, 443

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OFFSET

1,1

COMMENTS

A118953(A049084(a(n))) = 0; A065381 is a subsequence.

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

MAPLE

filter:= proc(n) not isprime(n-2^ilog2(n)) end proc:

select(filter, [seq(ithprime(i), i=1..100)]); # Robert Israel, Jan 27 2021

MATHEMATICA

okQ[n_] := !PrimeQ[n-2^(Length[IntegerDigits[n, 2]]-1)];