A187127 Triangular numbers k*(k+1)/2 mod 100, sorted and uniqued.

0, 1, 3, 5, 6, 10, 11, 15, 16, 20, 21, 25, 26, 28, 30, 31, 35, 36, 40, 41, 45, 46, 50, 51, 53, 55, 56, 60, 61, 65, 66, 70, 71, 75, 76, 78, 80, 81, 85, 86, 90, 91, 95, 96

Offset

1,3

Comments

Possible last two digits of triangular numbers k*(k+1)/2 (leading zeros omitted).

All triangular numbers less than 100 belong to this sequence. The sequence is finite with 44 terms: a(44)=96 is the last term.

Links

Table of n, a(n) for n=1..44.

Example

The last two digits of k*(k+1)/2  can be 00, 01, 03, 20, 91, etc., but not 02, 04, 12, 97, etc.

Mathematica

Union[Table[Mod[n*(n + 1)/2, 100], {n, 1, 100}]]

Crossrefs

Cf. A000217, A010461.

Sequence in context: A175304 A140951 A190243 * A187126 A065873 A072282

Adjacent sequences: A187124 A187125 A187126 * A187128 A187129 A187130

Keyword

base,fini,full,nonn

Author

Shyam Sunder Gupta, Aug 30 2013

Status

approved