login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A165158 Hypotenuses of primitive Pythagorean triangles such that all 3 sides are composite. 3

%I

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

%T 485,493,505,533,545,565,625,629,685,689,697,725,745,785,793,845,865,

%U 901,905,925,949,965,985,1025,1037,1073,1105,1145,1157,1165,1189,1205,1241

%N Hypotenuses of primitive Pythagorean triangles such that all 3 sides are composite.

%C Numbers C in triples of the form A^2+B^2=C^2, gcd(A,B,C)=1 and all of A, B and C in A002808.

%C If multiple solutions exist for the same C, as for example (A,B,C) = (16,63,65) and (33,56,65),

%C only one instance of C is added to the sequence.

%e (A,B,C) = (16,63,65), (36,77,85), (44,117,125) etc

%t lst={};Do[Do[If[IntegerQ[a=Sqrt[c^2-b^2]]&&GCD[a,b,c]==1,If[a>=b,Break[]]; If[ !PrimeQ[a]&&!PrimeQ[b]&&!PrimeQ[c],AppendTo[lst,c]]],{b,c-1,4, -1}],{c,5,2000,1}];Union@lst

%Y Cf. A020882, A165159

%K nonn

%O 1,1

%A _Vladimir Joseph Stephan Orlovsky_, Sep 06 2009

%E Typo in description corrected by _Alan Frank_, Oct 09 2009

%E Definition clarified, comment moved to the examples and new comment added - _R. J. Mathar_, Oct 21 2009

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified January 24 18:53 EST 2022. Contains 350565 sequences. (Running on oeis4.)