A109768 a(n) = gcd(3^n-2,2^n-3).

1, 1, 5, 1, 1, 1, 5, 1, 1, 1, 5, 1, 1, 1, 5, 1, 1, 1, 5, 1, 1, 1, 5, 1, 1, 1, 5, 1, 1, 1, 5, 1, 1, 1, 5, 1, 1, 1, 5, 1, 1, 1, 5, 1, 1, 1, 5, 1, 1, 1, 5, 1, 1, 1, 5, 1, 1, 1, 5, 1, 1, 1, 5, 1, 1, 1, 5, 1, 1, 1, 5, 1, 1, 1, 5, 1, 1, 1, 5, 1, 1, 1, 5, 1, 1, 1, 5

Offset

1,3

Comments

The first time the inequality a(n) > 5 occurs for n = A196628(2) = 3783 with a(3783) = 26665 = 5*5333 = A196627(1)*A196627(2). - Max Alekseyev, Oct 04 2011

Links

Antti Karttunen, Table of n, a(n) for n = 1..10000

Suggested by Max Alekseyev in a Seqfan memo Aug 09 2005.

Anatoly S. Izotov, On prime divisors of GCD(3^n-2,2^n-3), Fibonacci Quarterly 43, May 2005, pp. 130-131.

Mathematica

Table[GCD[3^n - 2, 2^n - 3], {n, 120}] (* Michael De Vlieger, Mar 10 2016 *)

Prog

(PARI) a(n) = gcd(3^n-2, 2^n-3); \\ Michel Marcus, Mar 10 2016

Crossrefs

Cf. A196627, A196628.

Sequence in context: A348505 A051008 A304042 * A069293 A347398 A333751

Adjacent sequences: A109765 A109766 A109767 * A109769 A109770 A109771

Keyword

nonn,changed

Author

John W. Layman, Aug 13 2005

Status

approved