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

1,119

Links

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

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}]

Crossrefs

Cf. A058529, A198441.

Sequence in context: A285936 A322358 A322437 * A336835 A353418 A361161

Adjacent sequences: A330171 A330172 A330173 * A330175 A330176 A330177

Keyword

nonn

Author

Ray Chandler, Feb 15 2020

Status

approved