
EXAMPLE

a(28) = 10; The divisors of 28 are {1,2,4,7,14,28}. The pairs of squarefree divisors of 28, (d1,d2), such that d1 <= d2 are (1,1), (1,2), (1,7), (1,14), (2,2), (2,7), (2,14), (7,7), (7,14) and (14,14). So a(28) = 10.
a(29) = 3; The divisors of 29 are {1,29}. The pairs of squarefree divisors of 29, (d1,d2), such that d1 <= d2 are (1,1), (1,29) and (29,29). So a(29) = 3.
a(30) = 36; The divisors of 30 are {1,2,3,5,6,10,15,30}. The 36 pairs of squarefree divisors of 30, (d1,d2) such that d1 <= d2 are (1,1), (1,2), (1,3), (1,5), (1,6), (1,10), (1,15), (1,30), (2,2), (2,3), (2,5), (2,6), (2,10), (2,15), (2,30), (3,3), (3,5), (3,6), (3,10), (3,15), (3,30), (5,5), (5,6), (5,10), (5,15), (5,30), (6,6), (6,10), (6,15), (6,30), (10,10), (10,15), (10,30), (15,15), (15,30), (30,30). So a(30) = 36.
a(31) = 3; The divisors of 31 are {1,31}. The pairs of squarefree divisors of 31 are (1,1), (1,31) and (31,31). So a(31) = 3.
