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A158031
Sides of equilateral triangles which are filled exactly (no holes, no overlaps) by the digits used to write a subsequence of consecutive triangular numbers, starting with 0.
1
1, 2, 3, 4, 8, 9, 11, 12, 14, 17, 22, 25, 30, 33, 36, 38, 41, 43, 46, 48, 51, 53, 56, 58, 61, 63, 65, 66, 69, 74, 77, 78, 81, 86, 89, 90, 93, 98, 101, 102, 105, 110, 113, 114, 117, 122, 125, 126, 132, 133, 139, 140, 146, 147, 153, 154, 160, 161, 167, 168, 174, 175, 181
OFFSET
1,2
COMMENTS
The triangular numbers fitting exactly in a "triangulars-digits triangle" are given by A158030. 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 above "equilateral" triangles, filled exactly by a subsequence of consecutive triangular numbers starting with 0 have sides 1, 2, 3, 4. The next properly filled triangle will have side 8.
CROSSREFS
Sequence in context: A111020 A002971 A157318 * A139461 A126421 A116111
KEYWORD
base,nonn
AUTHOR
Eric Angelini, Mar 11 2009
STATUS
approved