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Composite hypotenuses of primitive Pythagorean triangles.
4

%I #16 Nov 28 2019 13:54:57

%S 25,65,85,125,145,169,185,205,221,265,289,305,325,365,377,425,445,481,

%T 485,493,505,533,545,565,625,629,685,689,697,725,745,785,793,841,845,

%U 865,901,905,925,949,965,985,1025,1037,1073,1105,1145,1157,1165,1189,1205

%N Composite hypotenuses of primitive Pythagorean triangles.

%C Composite entries of A008846. Disjoint union of A024409 and A146945.

%H Ray Chandler, <a href="/A120961/b120961.txt">Table of n, a(n) for n = 1..10000</a>

%H César Aguilera, <a href="https://hal.archives-ouvertes.fr/hal-02151737">On Pythagorean Triples</a>, hal-02151737 preprint [math.NT], 2019.

%t lst = {}; Do[ If[ GCD[m, n] == 1, a = 2 m*n; b = m^2 - n^2; c = m^2 + n^2; If[ !PrimeQ@c, AppendTo[lst, c]]], {m, 3, 300}, {n, If[ OddQ@m, 2, 1], m - 1, 2}]; Take[ Union@ lst, 51] (* _Robert G. Wilson v_, May 02 2009 *)

%Y Cf. A120960, A008846, A146945, A024409.

%K nonn

%O 1,1

%A _Lekraj Beedassy_, Jul 19 2006

%E Term 485, which satisfies 485^2 = 476^2 + 93^2, added by _Robert G. Wilson v_, May 02 2009