A117677 a(n) = number of divisors of n^2 (excluding 1 and n^2).
0, 1, 1, 3, 1, 7, 1, 5, 3, 7, 1, 13, 1, 7, 7, 7, 1, 13, 1, 13, 7, 7, 1, 19, 3, 7, 5, 13, 1, 25, 1, 9, 7, 7, 7, 23, 1, 7, 7, 19, 1, 25, 1, 13, 13, 7, 1, 25, 3, 13, 7, 13, 1, 19, 7, 19, 7, 7, 1, 43, 1, 7, 13, 11, 7, 25, 1, 13, 7, 25, 1, 33, 1, 7, 13, 13, 7, 25, 1, 25, 7, 7, 1, 43, 7, 7, 7, 19, 1, 43, 7
Offset: 1
Links
- Harvey P. Dale, Table of n, a(n) for n = 1..1000
Programs
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Mathematica
Join[{0},DivisorSigma[0,Range[2,100]^2]-2] (* Harvey P. Dale, Oct 17 2016 *)
Formula
a(n) = A070824(n^2). - Ray Chandler, Nov 08 2018