A158030 Triangular numbers t such that all the digits needed to write the consecutive triangular numbers from 0 to t fill exactly an equilateral triangle (no holes, no overlaps).
0, 3, 10, 21, 153, 210, 378, 496, 820, 1431, 3081, 4656, 8646, 11628, 15051, 17766, 22578, 26335, 32896, 37950, 46665, 53301, 64620, 73153, 87571, 98346, 108345, 113526, 130305, 162735, 185136, 193131, 218791, 267546, 300700, 312445, 349866
Offset: 1
Examples
...0....0....0.....0 ........13...13....13 .............610...610 ...................1521 The triangular numbers fitting exactly in the SE corner of the above triangles are 0, 3, 10, 21.
Links
- Eric Angelini, Digit Spiral
- E. Angelini, Digit Spiral [Cached copy, with permission]
Comments