A127735 Triangle read by rows: A127701 * A002260 as infinite lower triangular matrices.

1, 3, 4, 4, 8, 9, 5, 10, 15, 16, 6, 12, 18, 24, 25, 7, 14, 21, 28, 35, 36, 8, 16, 24, 32, 40, 48, 49, 9, 18, 27, 36, 45, 54, 63, 64, 10, 20, 30, 40, 50, 60, 70, 80, 81, 11, 22, 33, 44, 55, 66, 77, 88, 99, 100, 12, 24, 36, 48, 60, 72, 84, 96, 108, 120, 121, 13, 26, 39, 52, 65, 78, 91, 104, 117, 130, 143, 144

Offset

1,2

Links

Table of n, a(n) for n=1..78.

Formula

Row sums = A127736: (1, 7, 21, 46, 85, 141, ...).

T(n,n) = n^2. T(n,k) = k*(n+1), 1<=k<n. - R. J. Mathar, Jul 21 2009

Example

First few rows of the triangle are:
1;
3, 4;
4, 8, 9;
5, 10, 15, 16;
6, 12, 18, 24, 25;
...

Crossrefs

Cf. A002260, A127701, A127736.

Sequence in context: A294113 A339827 A240875 * A330249 A075550 A292729

Adjacent sequences: A127732 A127733 A127734 * A127736 A127737 A127738

Keyword

nonn,tabl

Author

Gary W. Adamson, Jan 26 2007

Extensions

A-number of left factor in the definition corrected by R. J. Mathar, Jul 21 2009

a(19) corrected and more terms from Georg Fischer, Jun 05 2023

Status

approved