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A187126
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Triangular numbers k*(k+1)/2 mod 1000, sorted and uniqued.
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1
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0, 1, 3, 5, 6, 10, 11, 15, 16, 20, 21, 25, 26, 28, 30, 31, 35, 36, 40, 41, 45, 46, 50, 51, 55, 56, 60, 61, 65, 66, 70, 71, 75, 76, 78, 80, 81, 85, 86, 90, 91, 95, 96, 100, 101, 105, 106, 110, 111, 115, 116, 120, 121, 125, 126, 128, 130, 131, 135, 136, 140
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OFFSET
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1,3
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COMMENTS
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Possible last three digits of triangular numbers k*(k+1)/2 (leading zeros omitted).
All triangular numbers less than 1000 belong to this sequence. The sequence is finite with 424 terms: a(424)=996 is the last term.
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LINKS
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EXAMPLE
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The last three digits of k*(k+1)/2 can be 000, 001, 003, 021, 140, etc., but not 002, 004, 012, 139 etc.
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MATHEMATICA
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Union[Table[Mod[n*(n + 1)/2, 1000], {n, 1, 1000}]]
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CROSSREFS
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KEYWORD
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base,fini,full,nonn
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AUTHOR
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STATUS
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approved
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