A134999 Triangle-shaped numbers.

100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 148, 149, 150, 151

Offset: 1

Author

Omar E. Pol, Dec 05 2007

Keywords

• base
• nonn

Comments

The structure of digits represents a triangle. Three digits are the vertex. In the graphic representation the points are connected by imaginary line segments. All 3-digit numbers are terms of this sequence, except for the straight-line numbers A135643. For 4 or more digits the terms are 1000, 1011, 1012, 1024, 1034, 1036, ...

Examples

			The triangle number 1024:
  . . . 4
  . . . .
  . . 2 .
  1 . . .
  . 0 . .
		

Crossrefs

Cf. A134810, A135600, A135601, A135602, A135603, A135643.

Not to be confused with the triangular numbers, A000217!