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A109768 a(n) = gcd(3^n-2,2^n-3). 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 (list; graph; refs; listen; history; text; internal format)
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
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
Sequence in context: A348505 A051008 A304042 * A069293 A347398 A333751
KEYWORD
nonn
AUTHOR
John W. Layman, Aug 13 2005
STATUS
approved

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Last modified June 24 10:07 EDT 2024. Contains 373674 sequences. (Running on oeis4.)