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Search: id:A069712
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| A069712 |
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Triangular numbers with arithmetic mean of digits = integer (sum of digits = A multiple of the number of digits). |
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+0
4
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| 1, 3, 6, 15, 28, 55, 66, 91, 105, 120, 153, 171, 210, 231, 276, 300, 351, 378, 435, 465, 528, 561, 630, 666, 741, 780, 861, 903, 990, 1128, 1326, 1830, 2145, 2415, 3081, 5151, 5995, 6105, 7140, 8385, 8646, 9591, 9870, 10153, 11026, 11175, 12246, 12403
(list; graph; listen)
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OFFSET
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0,2
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MATHEMATICA
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Do[ If[ IntegerQ[ Apply[ Plus, IntegerDigits[n(n + 1)/2]] / Floor[ Log[10, n(n + 1)/2] + 1]], Print[n(n + 1)/2]], {n, 1, 10^3}]
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CROSSREFS
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Cf. A069709, A069710, A069711.
Adjacent sequences: A069709 A069710 A069711 this_sequence A069713 A069714 A069715
Sequence in context: A134774 A056278 A000740 this_sequence A076971 A103529 A034953
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KEYWORD
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base,nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Apr 08 2002
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EXTENSIONS
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Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 12 2002
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