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A074236 Numbers that can be the larger leg of some integer right triangle and hypotenuse of some other integer right triangle. 0
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A009003 gives ordered values of hypotenuse in i.r.t., A009012 gives ordered values of larger leg in i.r.t.. Intersection of them gives the 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 member because it is a larger leg in i.r.t. with sides 8, 15, 17 and hypotenuse in i.r.t. 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

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Last modified July 10 13:04 EDT 2020. Contains 335576 sequences. (Running on oeis4.)