A080045 Denominators of triangular array: T(n,1)=T(n,n)=1/n and T(n,k)=T(n-1,k-1)+t(n-1,k), 1<k<n.

1, 2, 2, 3, 1, 3, 4, 3, 3, 4, 5, 12, 3, 12, 5, 6, 60, 4, 4, 60, 6, 7, 20, 30, 2, 30, 20, 7, 8, 140, 60, 15, 15, 60, 140, 8, 9, 280, 105, 60, 15, 60, 105, 280, 9, 10, 2520, 840, 140, 12, 12, 140, 840, 2520, 10, 11, 2520, 252, 168, 210, 6, 210, 168, 252, 2520, 11, 12, 27720

Offset

1,2

Links

Table of n, a(n) for n=1..68.

Example

Triangle begins:.................Denominators:
.............1/1.........................1
..........1/2...1/2....................2...2
.......1/3...1/1...1/3...............3...1...3
....1/4...4/3...4/3...1/4..........4...3...3...4
.1/5..19/12..8/3..19/12..1/5.....5..12...8..12...5.

Crossrefs

Cf. A007318, A080044.

Sequence in context: A217029 A331886 A205456 * A191384 A191305 A227287

Adjacent sequences: A080042 A080043 A080044 * A080046 A080047 A080048

Keyword

nonn,tabl,frac

Author

Reinhard Zumkeller, Jan 21 2003

Status

approved