A127773 Triangle read by rows: row n consists of n-1 zeros followed by n(n+1)/2.

1, 0, 3, 0, 0, 6, 0, 0, 0, 10, 0, 0, 0, 0, 15, 0, 0, 0, 0, 0, 21, 0, 0, 0, 0, 0, 0, 28, 0, 0, 0, 0, 0, 0, 0, 36, 0, 0, 0, 0, 0, 0, 0, 0, 45, 0, 0, 0, 0, 0, 0, 0, 0, 0, 55

Offset

1,3

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

First few rows of the triangle are:
1;
0, 3;
0, 0, 6;
0, 0, 0, 10;
0, 0, 0, 0, 15;
...

Mathematica

Flatten[Table[{(n(n+1))/2, Table[0, {n}]}, {n, 10}]]  (* Harvey P. Dale, Apr 03 2011 *)
Table[PadLeft[{n (n+1)/2}, n, 0], {n, 10}]//Flatten (* Harvey P. Dale, Jan 18 2025 *)

Crossrefs

Cf. A127648, A000217, A127774.

Sequence in context: A273089 A362021 A330735 * A194498 A193986 A376203

Adjacent sequences: A127770 A127771 A127772 * A127774 A127775 A127776

Keyword

nonn,easy,tabl

Author

Gary W. Adamson, Jan 28 2007

Status

approved