A167194 Triangle read by rows. A130713 in the columns.

1, 2, 1, 1, 2, 1, 0, 1, 2, 1, 0, 0, 1, 2, 1, 0, 0, 0, 1, 2, 1, 0, 0, 0, 0, 1, 2, 1, 0, 0, 0, 0, 0, 1, 2, 1, 0, 0, 0, 0, 0, 0, 1, 2, 1, 0, 0, 0, 0, 0, 0, 0, 1, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 1

Offset: 1

Author

Mats Granvik, Oct 30 2009

Keywords

• nonn
• tabl

Examples

			Table begins:
  1;
  2,1;
  1,2,1;
  0,1,2,1;
  0,0,1,2,1;
  0,0,0,1,2,1;
  0,0,0,0,1,2,1;
  0,0,0,0,0,1,2,1;
  0,0,0,0,0,0,1,2,1;
  0,0,0,0,0,0,0,1,2,1;
  0,0,0,0,0,0,0,0,1,2,1;
  ...
		

Crossrefs

Cf. A004736, A130713, A185018.

Programs

Mathematica

Array[PadLeft[{1, 2, 1}, #] &,15] (* Paolo Xausa, Jun 27 2024 *)

Formula

From Peter Bala, Sep 12 2012: (Start)

T(n,k) = binomial(2,n-k).

O.g.f.: (1+x)^2/(1-t*x).

Riordan array ((1+x)^2,x).

Matrix inverse is signed version of A004736. (End)