|
| |
|
|
A078927
|
|
Smallest s for which there are exactly n primitive Pythagorean triangles with perimeter 2s; i.e. smallest s such that A078926(s) = n.
|
|
2
| | |
|
|
|
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.
|
|
|
EXAMPLE
| a(2)=858; the primitive Pythagorean triangles with edge lengths (364, 627, 725) and (195, 748, 773) both have perimeter 2*858=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[s=1, True, s++, If[ct[2s]==n, Return[s]]]
|
|
|
CROSSREFS
| a(n) = A078928(n)/2. Cf. A078926.
Sequence in context: A045480 A006114 A201141 * A064430 A180992 A137801
Adjacent sequences: A078924 A078925 A078926 * A078928 A078929 A078930
|
|
|
KEYWORD
| nonn,more
|
|
|
AUTHOR
| Dean Hickerson (dean.hickerson(AT)yahoo.com), Dec 15 2002
|
|
|
EXTENSIONS
| a(8) from Robert G. Wilson v (rgwv(AT)rgwv.com), Dec 19 2002
|
| |
|
|
