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|Mod[C(n, j), C(n, 2)]=0, j=0..n}; For n=1 Mod[1, 0] does not exist.

Example

The relevant residues are for n=16: {1, 16, 0, 80, 20, 48, 88, 40, 30, 40, 88, 48, 20, 80, 0, 16, 1}, a(16)=2; n=227: only with 6 nonzero residues: {1, 227, [111 zero], 454, 454, [111 zeros], 227, 1}

Crossrefs

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