A068503 Highest power of 3 dividing prime(n)-1.

1, 1, 1, 3, 1, 3, 1, 9, 1, 1, 3, 9, 1, 3, 1, 1, 1, 3, 3, 1, 9, 3, 1, 1, 3, 1, 3, 1, 27, 1, 9, 1, 1, 3, 1, 3, 3, 81, 1, 1, 1, 9, 1, 3, 1, 9, 3, 3, 1, 3, 1, 1, 3, 1, 1, 1, 1, 27, 3, 1, 3, 1, 9, 1, 3, 1, 3, 3, 1, 3, 1, 1, 3, 3, 27, 1, 1, 9, 1, 3, 1, 3, 1, 27, 3, 1, 1, 3, 1, 3, 1, 1, 243, 1, 3, 1, 1, 1, 9, 27

Offset: 1

Author

Benoit Cloitre, Mar 11 2002

Keywords

• easy
• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A006093, A038500, A099584.

Programs

Mathematica

a[n_] := 3^IntegerExponent[Prime[n] - 1, 3]; Array[a, 100] (* Amiram Eldar, May 14 2022 *)

PARI

a(n) = 3^valuation(prime(n)-1, 3); \\ Michel Marcus, Nov 24 2013

Formula

a(n) = A038500(A006093(n)). - Michel Marcus, Nov 24 2013

a(n) = 3^A099584(n). - Michel Marcus, Nov 24 2013