A361680 The n-th prime p such that p + 2^n is also prime.

3, 7, 11, 31, 47, 67, 83, 163, 179, 193, 263, 367, 389, 499, 563, 571, 887, 967, 1229, 1087, 1367, 1873, 1289, 2647, 1907, 2083, 1979, 2557, 2267, 3697, 2909, 3121, 3761, 4507, 4373, 4723, 5279, 5857, 6359, 6793, 7727, 8167, 7853, 6823, 6779, 8059, 9479, 10567

Offset

1,1

Comments

This sequence is non-monotonic: a(19) = 1229 > a(20) = 1087.

Links

Alois P. Heinz, Table of n, a(n) for n = 1..1000

Formula

a(n) = A361679(n,n).

Maple

b:= proc() option remember; local f; f:= proc() [] end;
      proc(n, k) option remember; local p;
        p:= `if`(nops(f(k))=0, 1, f(k)[-1]);
        while nops(f(k))<n do p:= nextprime(p);
          if isprime(p+2^k) then f(k):= [f(k)[], p] fi
        od; f(k)[n]
      end
    end():
a:= n-> b(n$2):
seq(a(n), n=1..55);

Crossrefs

Main diagonal of A361679.

Cf. A000040.

Sequence in context: A152084 A274134 A131588 * A091938 A333424 A186893

Adjacent sequences: A361677 A361678 A361679 * A361681 A361682 A361683

Keyword

nonn

Author

Alois P. Heinz, Mar 20 2023

Status

approved