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Search: id:A068071
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| A068071 |
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Triangular number remains triangular when the least significant digit is moved to the beginning. |
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+0
1
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| 1, 3, 6, 10, 55, 66, 210, 253, 666, 780, 4851, 8911, 15400, 17766, 125751, 303810, 407253, 906531, 1125750, 2648451, 5925403, 6706953, 15772536, 22207780, 50085036, 78406503, 438094800, 1623331710, 1764803755, 3437158416
(list; graph; listen)
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OFFSET
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1,2
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EXAMPLE
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8911, T133, is in the sequence because 8911 becomes 1891 which is T61.
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MATHEMATICA
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Do[k = FromDigits[ RotateRight[ 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
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Cf. A067269.
Sequence in context: A160965 A069708 A061455 this_sequence A067269 A071299 A061380
Adjacent sequences: A068068 A068069 A068070 this_sequence A068072 A068073 A068074
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KEYWORD
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base,nonn
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AUTHOR
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Robert G. Wilson v (rgwv(AT)rgwv.com), Feb 28 2002
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