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A187126 Triangular numbers k*(k+1)/2 mod 1000, sorted and uniqued. 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
COMMENTS
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.
LINKS
EXAMPLE
The last three digits of k*(k+1)/2 can be 000, 001, 003, 021, 140, etc., but not 002, 004, 012, 139 etc.
MATHEMATICA
Union[Table[Mod[n*(n + 1)/2, 1000], {n, 1, 1000}]]
CROSSREFS
Sequence in context: A140951 A190243 A187127 * A065873 A072282 A028727
KEYWORD
base,fini,full,nonn
AUTHOR
Shyam Sunder Gupta, Aug 30 2013
STATUS
approved

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Last modified March 28 20:05 EDT 2024. Contains 371254 sequences. (Running on oeis4.)