A130611 Tribonacci numbers A000073 which can be the hypotenuse of a Pythagorean triple.

13, 149, 274, 1705, 19513, 35890, 66012, 121415, 755476, 1389537, 4700770

Offset: 1

Author

Jonathan Vos Post, Jun 17 2007

Keywords

• nonn

Comments

The first 2 values are hypotenuses of primitive Pythagorean triples, A000073 INTERSECTION A020882: (5^2 + 12^2 = 13^2), (51^2 + 140^2 = 149^2). The other values listed have one or more nonprimitive solution: a(6) = 35890 has 13 solutions; a(8), a(9), a(10), a(11) have 4 solutions each.

Examples

			a(4) = 1705 because 1023^2 + 1364^2 = 1705^2, which is a nonprimitive Pythagorean triple 341*(3,4,5).
		

Crossrefs

Cf. A000073, A020882, A009000.

Formula

A000073 INTERSECTION A009000. {c in A000073 such that there exist integers a, b with a^2 + b^2 = c^2}.