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 A193562 Number of divisors of n^4+1. 2

%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

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Last modified February 17 15:19 EST 2019. Contains 320220 sequences. (Running on oeis4.)