A383615 Length of the long leg of the unique primitive Pythagorean triple (x,y,z) such that (x-y+z)/2 = A000108(n) and its long leg and hypotenuse are consecutive natural numbers.

4, 40, 364, 3444, 34584, 367224, 4086940, 47268364, 564177640, 6911470020, 86537568264, 1103799334200, 14305253278320, 187980019758360, 2500329584942460, 33615542888998620, 456277454520102600, 6246438361923425820, 86175353763393711960, 1197196443738946826760

Offset: 2

Author

Miguel-Ángel Pérez García-Ortega, May 02 2025

Keywords

• nonn
• easy

Examples

			Triangles begin:
  n=2:      3,     4,     5;
  n=3:      9,    40,    41.
This sequence is column 2.
		

Links

• Miguel-Ángel Pérez García-Ortega, El Libro de las Ternas Pitagóricas

Crossrefs

Cf. A000108, A131428 (short leg), A383616 (semiperimeter), A381846 (area).

Formula

a(n) = 2*C(n)*(C(n) - 1) where C(n) = A000108(n).