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

2,1

Links

Table of n, a(n) for n=2..77.

Formula

a(n) = Cardinality{j | C(n,2) divides C(n,j), j=0..n}.

Example

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.

Crossrefs

Cf. A060430, A014070.

Sequence in context: A256794 A366899 A068929 * A174543 A260450 A036583

Adjacent sequences: A060564 A060565 A060566 * A060568 A060569 A060570

Keyword

nonn

Author

Labos Elemer, Apr 12 2001

Status

approved