A234813 Number of distinct integers of the form i+(i+1)+(i+2)+...+j, for 1 <= i <= j <= n.

1, 3, 5, 9, 12, 16, 21, 27, 33, 40, 47, 55, 63, 70, 77, 89, 101, 110, 123, 134, 146, 159, 171, 186, 200, 214, 229, 245, 260, 275, 293, 312, 329, 349, 369, 388, 411, 432, 451, 474, 496, 519, 542, 564, 586, 611, 635, 660, 689, 713

Offset: 1

Author

Jeffrey Shallit, Apr 19 2014

Keywords

• nonn

Comments

See also A001227 = number of ways to write n as difference of triangular numbers. - M. F. Hasler, Apr 20 2014

Examples

			a(3) = 5 because the possible integers are 1,2,3=1+2,5=2+3,6=1+2+3.