A330174 Number of primitive Pythagorean triangles with sum of legs n.

0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 2

Offset: 1

Author

Ray Chandler, Feb 15 2020

Keywords

• nonn

Links

• Ray Chandler, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A058529, A198441.

Programs

Mathematica

f[n_]:=Block[{ps,sps}, ps=First/@FactorInteger[n];
sps=Select[ps,MemberQ[{1,7},Mod[#,8]]&];
If[sps==ps&&n!=1,2^(Length[ps]-1),0]];  Table[f[n],{n,120}]