A339307 Numbers k such that A228553(k) is prime.

11, 20, 24, 27, 32, 35, 37, 38, 68, 74, 78, 79, 82, 96, 98, 101, 103, 122, 137, 149, 161, 188, 209, 218, 239, 249, 258, 276, 293, 321, 325, 333, 363, 365, 372, 433, 445, 449, 499, 535, 567, 568, 580, 588, 594, 595, 622, 644, 656, 663, 666, 682, 688, 693, 721, 742, 754, 756, 760, 796, 814, 845

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..5000

Example

a(3) = 24 is in the sequence because A228553(24) = 1987 is prime.

Maple

f:= proc(n)
  local S;
  S:= select(t -> isprime(t) and isprime(2*n-t), [seq(i, i=3..n, 2)]);
  add(t*(2*n-t), t=S)
end proc:
f(2):= 4:
select(isprime@f, [$1..1000]);

Crossrefs

Cf. A228553, A339309.

Sequence in context: A053715 A343770 A250203 * A038581 A044054 A044435

Adjacent sequences: A339304 A339305 A339306 * A339308 A339309 A339310

Keyword

nonn

Author

J. M. Bergot and Robert Israel, Nov 29 2020

Status

approved