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A067269
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Triangular numbers which remain triangular when the most significant digit is moved to the end.
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1
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1, 3, 6, 10, 55, 66, 300, 325, 666, 1035, 1485, 1891, 61776, 103740, 109746, 112575, 190653, 340725, 1026028, 1264845, 3000025, 3002475, 3592540, 3670695, 37840650, 60000535, 61577253, 65008503, 1001393128, 1432436050, 1560756385
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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EXAMPLE
| 1485 is a term as 1485 and 4851 both are triangular numbers.
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MATHEMATICA
| Do[k = FromDigits[ RotateLeft[ IntegerDigits[n(n + 1)/2]]]; l = Floor[ Sqrt[2k]]; If[k == l(l + 1)/2, Print[n(n + 1)/2]], {n, 1, 10^5}]
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CROSSREFS
| Sequence in context: A069708 A061455 A068071 * A071299 A061380 A125567
Adjacent sequences: A067266 A067267 A067268 * A067270 A067271 A067272
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KEYWORD
| base,nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Feb. 22 2002
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EXTENSIONS
| Edited by Robert G. Wilson v (rgwv(AT)rgwv.com), Feb. 28 2002
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