A071202 Array read by antidiagonals giving number of paths up and left from (0,0) to (n,k) where x/y<n/k (except at start and finish).

1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 2, 2, 2, 1, 1, 3, 5, 5, 3, 1, 1, 3, 7, 5, 7, 3, 1, 1, 4, 7, 14, 14, 7, 4, 1, 1, 4, 12, 19, 14, 19, 12, 4, 1, 1, 5, 15, 30, 42, 42, 30, 15, 5, 1, 1, 5, 15, 30, 66, 42, 66, 30, 15, 5, 1, 1, 6, 22, 55, 99, 132, 132, 99, 55, 22, 6, 1, 1, 6, 26, 67, 143, 202, 132

Offset

1,8

Links

Table of n, a(n) for n=1..85.

Formula

Some identities: a(n, k)=a(k, n); a(n, m*n)=a(n, m*n-1); a(n, n)=A000108(n-1); if n and k are coprime then a(n, k)=A071201(n, k)

Crossrefs

Sequence in context: A109338 A291191 A273866 * A207379 A220163 A102715

Adjacent sequences: A071199 A071200 A071201 * A071203 A071204 A071205

Keyword

nonn,tabl

Author

Henry Bottomley, May 16 2002

Status

approved