A143394 Least prime p such that p*(p + prime(n)) -+ 1 are twin primes, or 0 if no such prime exists.

0, 3, 0, 2, 3, 2, 3, 2, 109, 1291, 3, 557, 211, 3, 3, 7, 7, 3, 2, 13, 2, 5, 43, 97, 2, 3, 149, 43, 5, 3, 5, 13, 3, 2, 7, 3, 5, 197, 13, 73, 7, 11, 229, 23, 3, 5, 3, 23, 13, 2, 19, 7, 5, 109, 283, 67, 7, 3, 11, 13, 2, 43, 2, 19, 233, 7, 1061, 3, 3, 149, 43, 421, 11, 113, 29, 7, 991, 41, 61

Offset

1,2

Comments

No twin primes of the form p*(p+2) -+ 1 for p prime.

Only one pair of twin primes of the form p*(p+3) -+ 1 (it occurs at p=3).

No twin primes of the form p*(p+5) -+ 1 for p prime.

Links

Pierre CAMI, Table of n, a(n) for n = 1..12250

Example

3*(3+3) - 1 = 17 and 3*(3+3) + 1 = 19 are twin primes (and 2*(2+3) - 1 = 9 and 2*(2+3) + 1 = 11 are not twin primes) so a(2)=3.

Crossrefs

Cf. A143393.

Sequence in context: A032531 A301430 A328311 * A112455 A001608 A159977

Adjacent sequences: A143391 A143392 A143393 * A143395 A143396 A143397

Keyword

nonn

Author

Pierre CAMI, Aug 12 2008

Extensions

Edited by Jon E. Schoenfield, Jan 19 2019

Status

approved