OFFSET
1,1
COMMENTS
A Pythagorean triangle is a right triangle whose edge lengths are all integers; such a triangle is 'primitive' if the lengths are relatively prime.
Least perimeter common to exactly n primitive Pythagorean triangles. - Lekraj Beedassy, May 14 2004
LINKS
Derek J. C. Radden and Peter T. C. Radden, Table of n, a(n) for n=1..39 (terms 1 through 15 were computed by Derek J. C. Radden)
C. B. T. (Reviewer), Review of Andrew S. Anema, A table of primitive Pythagorean triangle with identical perimeters, Mathematical Tables and Other Aids to Computation, Vol. 10, No. 53 (Jan., 1956), pp. 35-36.
EXAMPLE
a(2)=1716; the primitive Pythagorean triangles with edge lengths (364, 627, 725) and (195, 748, 773) both have perimeter 1716.
MATHEMATICA
oddpart[n_] := If[OddQ[n], n, oddpart[n/2]]; ct[p_] := Length[Select[Divisors[oddpart[p/2]], p/2<#^2<p&&GCD[ #, p/2/# ]==1&]]; a[n_] := For[per=2, True, per+=2, If[ct[per]==n, Return[per]]]
CROSSREFS
KEYWORD
nonn
AUTHOR
Dean Hickerson, Dec 15 2002
EXTENSIONS
a(8) from Robert G. Wilson v, Dec 19 2002
a(9)-a(15) from Derek J C Radden, Dec 22 2012
a(16)-a(39) from Peter T. C. Radden, Dec 29 2012
STATUS
approved