A352616 Numbers k such that A155085(k) is in A037074.

7, 17, 50, 71, 449, 851, 881, 1467, 2591, 5123, 9521, 18167, 29817, 34859, 38027, 39761, 52415, 84359, 90611, 92711, 106721, 147267, 179999, 204479, 206081, 342791, 388961, 596231, 606609, 847601, 922607, 1060307, 1256879, 1292831, 1389671, 1590983, 1976015, 2157227, 2169971, 2268449, 2571911

Offset: 1

Author

J. M. Bergot and Robert Israel, Mar 23 2022

Keywords

• nonn

Comments

Numbers k such that k + A000203(k) is the product of a twin prime pair.

Examples

			a(3) = 50 is a term because 50 + A000203(50) = 143 = 11*13 where (11,13) is a twin prime pair.
		

Crossrefs

Cf. A000203, A037074, A155085.

Programs

Maple

filter:= proc(n) local t,s; t:= n + numtheory:-sigma(n);
  if t::even or not issqr(t+1) then return false fi;
  s:= sqrt(t+1);
  isprime(s+1) and isprime(s-1)
end proc:
select(filter, [$1..3000000]);