A074236 Numbers that are the long leg of some integer right triangle and the hypotenuse of some other integer right triangle.

15, 20, 30, 35, 40, 45, 52, 55, 60, 68, 70, 75, 80, 90, 91, 100, 104, 105, 110, 116, 117, 120, 135, 136, 140, 143, 148, 150, 153, 156, 160, 164, 165, 175, 180, 182, 187, 195, 200, 204, 208, 210, 212, 220, 221, 225, 232, 234, 240, 244, 245, 247, 255, 260, 270

Offset

1,1

Comments

A009003 gives ordered values of hypotenuses of integer right triangles; A009012 gives ordered values of long legs of integer right triangles. Their intersection is this sequence.

Note that all terms are composite.

Links

Table of n, a(n) for n=1..55.

Formula

Intersection of A009012 and A009003.

Example

15 is a term because it is the long leg of the integer right triangle with sides 8, 15, 17 and the hypotenuse of the integer right triangle with sides 9, 12, 15.

Mathematica

prims=With[{cps=Select[Subsets[Range[1, 221, 2], {2}], CoprimeQ@@#&]}, ptrip[ {a_, b_}]:={a*b, (b^2-a^2)/2, (b^2+a^2)/2}; Sort[Sort/@(ptrip/@cps)]]; pyths= Sort[Flatten[Table[n #&/@prims, {n, 200}], 1]]; Take[Intersection[ Transpose[ pyths][[2]], Transpose[pyths][[3]]], 80] (* Harvey P. Dale, Apr 26 2012 *)

Crossrefs

Cf. A009003, A009012.

Sequence in context: A066860 A120159 A163602 * A086770 A111200 A088494

Adjacent sequences: A074233 A074234 A074235 * A074237 A074238 A074239

Keyword

nonn

Author

Zak Seidov, Sep 18 2002

Extensions

Corrected by Harvey P. Dale, Apr 26 2012

Status

approved