OFFSET
1,1
COMMENTS
In most of the cases the n-th power that divides a(n)-1 is 2^n.
FORMULA
Empirical G.f.: -x*(3904*x^5-6104*x^4+2502*x^3-329*x^2+56*x-8) / ((x-1)*(2*x-1)*(4*x-1)*(8*x-1)). [Colin Barker, Feb 05 2013]
EXAMPLE
a(4) = 4913 = 17^3 and 4912 = (2^4)*307.
CROSSREFS
KEYWORD
nonn
AUTHOR
Amarnath Murthy, Sep 19 2003
EXTENSIONS
More terms from Ray Chandler, Oct 04 2003
STATUS
approved