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A068131
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Triangular numbers with sum of digits = 21.
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2
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1596, 2775, 3486, 3828, 4278, 4656, 5565, 6555, 7626, 8256, 9453, 14196, 15753, 16653, 17391, 18336, 21945, 22791, 23871, 24753, 28920, 32385, 34716, 37128, 38226, 39621, 40755, 42195, 43365, 44850, 46056, 51681, 54615, 56280, 57630
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,1
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COMMENTS
| 1. The sequence is unbounded, as the (5*10^k +6)-th triangular number is a term. 2. The sum of the digits of triangular numbers in most cases is a triangular number. 3. Conjecture: For every triangular number T there exist infinitely many triangular numbers with sum of digits = T.
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CROSSREFS
| Cf. A068127, A068128, A068129, A068130.
Sequence in context: A015281 A132654 A179248 * A068263 A078954 A117745
Adjacent sequences: A068128 A068129 A068130 * A068132 A068133 A068134
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KEYWORD
| base,easy,nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Feb 21 2002
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EXTENSIONS
| More terms from Sascha Kurz (sascha.kurz(AT)uni-bayreuth.de), Mar 06 2002
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