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

1,1

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, ...

Links

Table of n, a(n) for n=1..48.

Example

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!

Sequence in context: A112525 A000865 A135600 * A301516 A204581 A135641

Adjacent sequences: A134996 A134997 A134998 * A135000 A135001 A135002

Keyword

base,nonn

Author

Omar E. Pol, Dec 05 2007

Status

approved