cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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

Original entry on oeis.org

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

Views

Author

Zak Seidov, Sep 18 2002

Keywords

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.

Examples

			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.
		

Crossrefs

Programs

  • 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 *)

Formula

Intersection of A009012 and A009003.

Extensions

Corrected by Harvey P. Dale, Apr 26 2012
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