OFFSET
1,2
COMMENTS
All primes are the terms of a(n). Quotients A130072(p)/p for p = Prime(n) are listed in A130075(n) = {6,30,570,10830,4422630,93776970,44871187170,1003806502230,...}. p^(k+1) divides A130072(p^k) for prime p = {2,3,5,19} = A130076(n) and all k>0. Nonprimes n such that n divides A130072(n) are listed in A130074(n) = {1,4,6,8,9,12,15,16,18,24,25,27,32,36,44,45,48,54,64,72,75,81,95,96,...} which apparently include all powers p^k of primes p = {2,3,5,19} for k>1 and all powers of numbers of the form 2^k*3^m, 3^k*5^m, 5^k*19^m.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
MATHEMATICA
Select[Range[1000], IntegerQ[(PowerMod[5, #, # ]-PowerMod[3, #, # ]-PowerMod[2, #, # ])/# ]&]
PROG
(PARI) is(n)=Mod(5, n)^n==Mod(3, n)^n+Mod(2, n)^n \\ Charles R Greathouse IV, Nov 04 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Alexander Adamchuk, May 06 2007
STATUS
approved