A379609 Triples (x,y,z) such that T(x)*T(y) = T(z) with 2 <= x <= y, where T(n) is the n-th triangular number, sorted first by values of z, then by values of x.

3, 3, 8, 2, 5, 9, 4, 6, 20, 2, 20, 35, 3, 14, 35, 4, 12, 39, 5, 11, 44, 7, 10, 55, 5, 19, 75, 3, 34, 84, 9, 13, 90, 6, 21, 98, 2, 76, 132, 6, 33, 153, 4, 55, 175, 14, 18, 189, 13, 20, 195, 12, 23, 207, 15, 20, 224, 14, 22, 230, 11, 28, 231, 12, 29, 260, 7, 51, 272, 10, 38, 285, 11, 36, 296, 5, 90, 350, 3, 143, 351, 10, 50, 374, 7, 75, 399, 9, 68, 459, 19, 34, 475

Offset: 1

Author

Kelvin Voskuijl, Dec 27 2024

Keywords

• nonn
• tabf

Examples

			Triples begin:
  3,  3,  8;
  2,  5,  9;
  4,  6, 20;
  2, 20, 35;
  3, 14, 35;
  4, 12, 39;
  5, 11, 44;
  7, 10, 55;
  ...
The triple 2,5,9 is in this sequence because the second triangular number (3) times the fifth (15) is the ninth (45).
		

Crossrefs

Cf. A000217, A188630, A198453 (additive), A225390.