A110771 The r-th term of the n-th row of the following triangle is C[{T(n)-T(r-1)},r] where T(n) is the n-th triangular number. 1 3 1 6 10 1 10 36 35 1 ... Sequence contains the row sums.

1, 4, 17, 82, 453, 2855, 20279, 159972, 1383544, 12987671, 131301747, 1420538383, 16358806638, 199606632428, 2570446661320, 34814885202341, 494470158654963, 7344794248474716, 113829232686474480

Offset

1,2

Comments

The first term is T(n), the n-th term is 1.

Links

Table of n, a(n) for n=1..19.

Example

For n = 4 the terms of the 4th row are C(10,1), C(9,2), C(7,3), C(4,4). 10, 36, 35, 1 and the sum is a(4) = 82.

Mathematica

A110771[n_] := Plus @@ Table[Binomial[Binomial[n + 1, 2] - Binomial[r, 2], r], {r, 1, n}]; Table[A110771[i], {i, 1, 25}] (* Keith Schneider, Jul 03 2007 *)

Crossrefs

Cf. A110768, A110769, A110770.

Sequence in context: A078845 A230126 A181517 * A082028 A052315 A369476

Adjacent sequences: A110768 A110769 A110770 * A110772 A110773 A110774

Keyword

easy,nonn

Author

Amarnath Murthy, Aug 12 2005

Extensions

More terms from Keith Schneider, Jul 03 2007

Status

approved