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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).
1
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
1,2
COMMENTS
The sides of the successive triangles are given by A158031. Terms computed by Jean-Marc Falcoz.
LINKS
Eric Angelini, Digit Spiral
E. Angelini, Digit Spiral [Cached copy, with permission]
EXAMPLE
...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.
CROSSREFS
Sequence in context: A120109 A286067 A337623 * A068082 A058077 A161672
KEYWORD
base,nonn
AUTHOR
Eric Angelini, Mar 11 2009
STATUS
approved