A138066 Least k > 0 such that (2n-1)^k + 2 is prime, or 0 if no such number exists.

1, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 11, 0, 1, 1, 0, 2, 1, 0, 1, 1, 0, 1, 113, 0, 1, 7, 0, 1, 1, 0, 3, 1, 0, 1, 1, 0, 12, 1, 0, 1, 3, 0, 1, 255, 0, 8, 1, 0, 1, 1, 0, 1, 1, 0, 1, 3, 0, 2, 15, 0, 2, 1, 0, 1, 23, 0, 1, 1, 0, 4, 3, 0, 1, 1, 0, 3, 1, 0, 136, 1, 0, 1

Offset

1,12

Comments

a(3n+1) = 0 for n > 0.

a(84) > 100000. - Ray Chandler, Aug 10 2011

Links

Table of n, a(n) for n=1..83.

Crossrefs

Cf. A084713 (smallest prime of the form (2n-1)^k + 2, or 0 if no such number exists).

Cf. A138067 (least k > 1 such that (2n-1)^k + 2 is prime, or 0 if no such number exists).

Cf. A051783 (k such that 3^k + 2 is prime).

Cf. A087885 (k such that 5^k + 2 is prime).

Cf. A090649, A109076, A113480, A138048, A138049, A138050, A138051, A087886, A113481.

Sequence in context: A216726 A323169 A143197 * A173189 A115595 A342123

Adjacent sequences: A138063 A138064 A138065 * A138067 A138068 A138069

Keyword

hard,nonn

Author

Alexander Adamchuk, Mar 02 2008

Status

approved