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

Author

Shyam Sunder Gupta, Aug 30 2013

Keywords

• base
• fini
• full
• nonn

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.

Examples

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

Crossrefs

Cf. A000217, A010461.

Programs

Mathematica

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