A089059 Numbers x such that xy/(x+y) is an integer and the hypotenuse of the right triangle with legs x and y is an integer.

21, 42, 63, 84, 85, 105, 126, 147, 168, 170, 184, 189, 210, 217, 231, 252, 255, 273, 294, 315, 336, 340, 357, 368, 378, 399, 420, 425, 434, 441, 441, 462, 483

Offset

1,1

Comments

These numbers are almost always divisible by 7. 85 in the example is an exception and so is 184.

Links

Table of n, a(n) for n=1..33.

Example

x=85,y=204, 85^2+204^2 = 221^2

Prog

(PARI) xydivxpy2(n) = { for(x=1, n, for(y=x, n, h=x*y/(x+y); if(h==floor(h), z = sqrt (x^2+y^2); if(z==floor(z), print1(x", ") ) ) ) ) }

Crossrefs

Sequence in context: A192130 A258188 A037978 * A114384 A008603 A235497

Adjacent sequences: A089056 A089057 A089058 * A089060 A089061 A089062

Keyword

nonn

Author

Cino Hilliard, Dec 02 2003, corrected Nov 23 2006

Status

approved