%I
%S 1,2,2,4,2,4,2,4,4,8,4,4,4,4,4,8,2,4,4,8,2,4,4,4,2,8,4,8,2,4,4,8,4,8,
%T 2,4,4,8,4,4,4,8,4,16,8,8,2,8,2,8,4,8,4,8,2,8,2,4,4,16,8,4,4,8,8,4,8,
%U 8,4,8,8,4,4,4,2,8,8,16,4,16,2,4,2,16,4
%N Number of divisors of n^4+1.
%C This is to n^4+1 as A193432 is to n^2+1. a(n) = 2 when n^4+1 is prime, iff n is in A037896.
%F a(n) = A000005(A002523(n)) = d(n^4+1) (also called tau(n^4+1) or sigma_0(n^4+1)), the number of divisors of n^4+1.
%e a(3) = 4 because 3^4+1 = 82, whose 4 factors are {1, 2, 41, 82}.
%t DivisorSigma[0,Range[0,90]^4+1] (* _Harvey P. Dale_, May 05 2013 *)
%Y Cf. A000005, A002523, A037896, A193432 (number of divisors of n^2+1).
%K nonn,easy
%O 0,2
%A _Jonathan Vos Post_, Aug 09 2011
