OFFSET
1,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
FORMULA
a(n) = M / GCD( M, 5 ) where M=2^n-1.
Conjectures from Colin Barker, Aug 23 2014: (Start)
a(n) = 17*a(n-4)-16*a(n-8).
G.f.: x*(8*x^6+12*x^5+14*x^4+3*x^3+7*x^2+3*x+1) / ((x-1)*(x+1)*(2*x-1)*(2*x+1)*(x^2+1)*(4*x^2+1)).
(End)
MAPLE
MATHEMATICA
Table[(2^n - 1)/GCD[2^n - 1, 5], {n, 50}] (* Vincenzo Librandi, Mar 16 2013 *)
PROG
(Magma) [(2^n - 1) / GCD (2^n - 1, 5): n in [1..40]]; // Vincenzo Librandi, Mar 16 2013
(PARI) a(n)=(2^n-1)/gcd(2^n-1, 5) \\ Edward Jiang, Sep 04 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Joerg Arndt, Jun 07 2012
STATUS
approved