A338202 a(n) is the number of unit perimeter triangles with rational side lengths whose largest denominator is less than or equal to n.

0, 0, 1, 1, 2, 2, 4, 5, 7, 8, 12, 14, 19, 21, 26, 30, 38, 42, 52, 60, 70, 76, 90, 98, 113, 122, 138, 152, 173, 186, 210, 226, 249, 265, 306, 324, 357, 377, 410, 442, 482, 514, 558, 592, 645, 675, 727, 759, 813, 848, 902, 950, 1015, 1053, 1140, 1210, 1277, 1326

Offset

1,5

Comments

Partial sums of A338201.

a(n) is bounded above by A180360(n,3).

Links

Peter Kagey, Table of n, a(n) for n = 1..300

Example

For n = 8, the a(8) = 5 triangles have side lengths
1/3, 1/3, 1/3;
1/5, 2/5, 2/5;
2/7, 2/7, 3/7;
1/7, 3/7, 3/7; and
1/4, 3/8, 3/8.

Crossrefs

Cf. A180360, A338201.

Sequence in context: A120326 A036406 A029007 * A348552 A058678 A241410

Adjacent sequences: A338199 A338200 A338201 * A338203 A338204 A338205

Keyword

nonn

Author

Peter Kagey, Oct 16 2020

Status

approved