A060567 Number of binomial coefficients C(n,j) with j=0..n that are divisible by C(n,2).
3, 2, 1, 2, 2, 2, 4, 2, 2, 6, 5, 4, 10, 4, 2, 8, 10, 6, 12, 4, 6, 18, 10, 4, 14, 14, 6, 10, 23, 20, 22, 10, 18, 22, 10, 18, 34, 26, 15, 18, 24, 14, 32, 14, 10, 42, 28, 12, 28, 18, 12, 32, 34, 14, 25, 26, 42, 54, 30, 14, 58, 42, 22, 24, 28, 36, 60, 38, 20, 34, 44, 26, 70, 42, 20, 42
Offset: 2
Keywords
Examples
The relevant residues C(n,j) mod C(n,2) for n=16 are {1, 16, 0, 80, 20, 48, 88, 40, 30, 40, 88, 48, 20, 80, 0, 16, 1}, so a(16) = 2.
For n=227, there are only 6 nonzero residues; the residues are {1, 227, [111 zeros], 454, 454, [111 zeros], 227, 1}, so a(227) = 222.
Formula
a(n) = Cardinality{j | C(n,2) divides C(n,j), j=0..n}.