A332029 a(n) is the least number k > 0 such that n^k - (n mod 2) - 1 is prime, or 0 if no such number exists.

0, 2, 2, 1, 1, 1, 1, 1, 1, 0, 4, 1, 1, 1, 1, 0, 6, 1, 1, 1, 1, 0, 24, 1, 1, 0, 2, 0, 2, 1, 1, 1, 1, 0, 2, 0, 2, 1, 1, 0, 4, 1, 1, 1, 1, 0, 2, 1, 1, 0, 8, 0, 4, 1, 1, 0, 12, 0, 4, 1, 1, 1, 1, 0, 8, 0, 3, 1, 1, 0, 2, 1, 1, 1, 1, 0, 2, 0, 38, 1, 1, 0, 4, 1, 1, 0, 4

Offset

1,2

Links

Table of n, a(n) for n=1..87.

Formula

For k >= 1, a(2*k+2) = A101264(k), a(2*k-1) = A255707(k). - Jinyuan Wang, Feb 07 2020

a(n) = 0 for n in A238204. - Michel Marcus, Feb 08 2020 [Proof: a(n) = 1 iff n - 1 is a prime because n^k - 1 is divisible by n - 1, where k > 1 and n is an even number greater than 2. But if n is a term in A238204, n - m is prime only for some m >= 3. Therefore, a(n) = 0 for n in A238204. - Jinyuan Wang, Feb 08 2020]

Crossrefs

Cf. A101264, A255707.

Sequence in context: A102552 A131341 A124034 * A211312 A085978 A141044

Adjacent sequences: A332026 A332027 A332028 * A332030 A332031 A332032

Keyword

nonn

Author

Todor Szimeonov, Feb 05 2020

Extensions

More terms from Jinyuan Wang, Feb 07 2020

Status

approved