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A187126 Triangular numbers n*(n+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 n*(n+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

Shyam Sunder Gupta, Table of n, a(n) for n = 1..424

EXAMPLE

The last three digits of n*(n+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

Cf. A000217, A122986.

Sequence in context: A140951 A190243 A187127 * A065873 A072282 A028727

Adjacent sequences:  A187123 A187124 A187125 * A187127 A187128 A187129

KEYWORD

base,fini,full,nonn

AUTHOR

Shyam Sunder Gupta, Aug 30 2013

STATUS

approved

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Last modified February 21 01:03 EST 2020. Contains 332086 sequences. (Running on oeis4.)