A135151 A002260 + A128174 - I, I = Identity matrix.

1, 1, 2, 2, 2, 3, 1, 3, 3, 4, 2, 2, 4, 4, 5, 1, 3, 3, 5, 5, 6, 2, 2, 4, 4, 6, 6, 7, 1, 3, 3, 5, 5, 7, 7, 8, 2, 2, 4, 4, 6, 6, 8, 8, 9, 1, 3, 3, 5, 5, 7, 7, 9, 9, 10

Offset

1,3

Comments

A135152 is a companion triangle, both having row sums = A047838: (1, 3, 7, 11, 17, 23, 31, 39, ...).

Links

Table of n, a(n) for n=1..55.

Formula

A002260 + A128174 - I, where I = Identity matrix, A002260 = (1; 1,2; 1,2,3; ...) and A128174 = (1; 0,1; 1,0,1; 0,1,0,1; ...).

Example

First few rows of the triangle:
  1;
  1, 2;
  2, 2, 3;
  1, 3, 3, 4;
  2, 2, 4, 4, 5;
  1, 3, 3, 5, 5, 6;
  2, 2, 4, 4, 6, 6, 7;
  ...

Crossrefs

Cf. A002260, A047838, A135152.

Sequence in context: A240689 A233567 A141059 * A256855 A273943 A256071

Adjacent sequences: A135148 A135149 A135150 * A135152 A135153 A135154

Keyword

nonn,tabl

Author

Gary W. Adamson, Nov 21 2007

Status

approved