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

1,1

Comments

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

Links

Table of n, a(n) for n=1..41.

Example

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

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]);

Crossrefs

Cf. A000203, A037074, A155085.

Sequence in context: A045821 A262754 A115914 * A094534 A262106 A371715

Adjacent sequences: A352613 A352614 A352615 * A352617 A352618 A352619

Keyword

nonn

Author

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

Status

approved