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Number of divisors for each term in the triangle A055096. It is 2 for primes (all of the form 4k+1).
2

%I #7 Mar 31 2015 03:55:25

%S 2,4,2,2,6,3,4,2,4,2,2,8,6,6,2,6,2,4,4,4,4,4,6,2,10,2,9,2,4,4,12,2,4,

%T 6,8,4,2,8,2,6,4,8,2,6,2,4,4,8,2,4,2,8,4,4,4,4,6,6,12,3,18,2,10,9,6,4,

%U 8,2,4,4,4,4,4,2,8,2,8,2,2,12,4,6,4,8,6,12,2,8,2,12,4,4,2,12,2,8,6,4,3

%N Number of divisors for each term in the triangle A055096. It is 2 for primes (all of the form 4k+1).

%p sum2distinct_squares_array := (n) -> (((n-((trinv(n-1)*(trinv(n-1)-1))/2))^2)+((trinv(n-1)+1)^2));

%p with(numtheory, tau); a(n) = tau(sum2distinct_squares_array(n))

%Y Cf. A055132.

%K nonn,tabl

%O 1,1

%A _Antti Karttunen_, Apr 04 2000