1,12

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

a(84) > 100000. [From Ray Chandler, Aug 10 2011]

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

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 = Numbers n such that 3^n + 2 is prime. Cf. A087885 = Numbers n such that 5^n + 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

hard,nonn

Alexander Adamchuk, Mar 02 2008

approved