A104792 Triangle T(n,k) = A000330(n-k), n>=1, 0<=k<n, read by rows.

1, 5, 1, 14, 5, 1, 30, 14, 5, 1, 55, 30, 14, 5, 1, 91, 55, 30, 14, 5, 1, 140, 91, 55, 30, 14, 5, 1, 204, 140, 91, 55, 30, 14, 5, 1, 285, 204, 140, 91, 55, 30, 14, 5, 1, 385, 285, 204, 140, 91, 55, 30, 14, 5, 1, 506, 385, 285, 204, 140, 91, 55, 30, 14, 5, 1, 650, 506, 385, 285

Offset

1,2

Comments

Repeatedly writing the square pyramidal numbers (A000330) backwards.

Links

Table of n, a(n) for n=1..70.

Formula

T(n,k) = (n-k)(n-k+1)(2n-2k+1)/6 = A000330(A004736(n)). - Ralf Stephan, Apr 05 2009

Example

First few rows of the triangle are:
1;
5, 1;
14, 5, 1;
30, 14, 5, 1;
55, 30, 14, 5, 1;
91, 55, 30, 14, 5, 1;
...

Crossrefs

Row sums are in A002415. Antidiagonals are in A000332.

Sequence in context: A174504 A270654 A067558 * A120393 A370518 A094368

Adjacent sequences: A104789 A104790 A104791 * A104793 A104794 A104795

Keyword

nonn,easy,tabl

Author

Gary W. Adamson, Mar 26 2005

Extensions

Edited by Ralf Stephan, Apr 05 2009

Status

approved