A382393 Positive integers k such that 6*k - 1 is prime for k != 1 (mod 5) and (6*k - 1)/5 is prime for k == 1 (mod 5).

2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 22, 23, 25, 26, 28, 29, 30, 31, 32, 33, 36, 38, 39, 40, 42, 43, 44, 45, 47, 49, 51, 52, 53, 56, 58, 59, 60, 61, 64, 65, 66, 67, 70, 72, 74, 75, 77, 78, 80, 81, 82, 84, 85, 86, 87, 91, 93, 94, 95, 98, 99, 100

Offset

1,1

Comments

For all elements of this sequence, there are no pairs (x,y) of positive integers with x > 1 such that a(n)=6*x*y+x-y.

Links

Table of n, a(n) for n=1..69.

Prog

(PARI) select(k->isprime((6*k-1)/(5-4*!(k==Mod(1, 5)))), vector(100, i, i))

Crossrefs

Cf. A024898, A024899.

Sequence in context: A244511 A014157 A026467 * A088185 A118844 A379808

Adjacent sequences: A382390 A382391 A382392 * A382394 A382395 A382396

Keyword

nonn

Author

V. Barbera, Mar 23 2025

Status

approved