OFFSET
1,1
COMMENTS
It is an open problem to find all numbers n such that (n+1)(n-1) is a divisor of 3^n + 5^n.
Such n together with n^2 must belong to this sequence (an example is given by n=3). Furthermore, it is not known if the intersection of this sequence and A234536 equals {3}. - Max Alekseyev, May 19 2015
LINKS
Daniel Kohen et al., On Polynomials dividing Exponentials, MathOverflow
Byron Schmuland et al., Find all positive integers n such that 3^n + 5^n is divisible by n^2 - 1, Math StackExchange
MATHEMATICA
Select[Range[2, 10^6], Mod[PowerMod[3, #, # - 1] + PowerMod[5, #, # - 1], # - 1] == 0 &]
CROSSREFS
KEYWORD
nonn
AUTHOR
Siad Daboul, Dec 27 2013
STATUS
approved