A120681 Sum of legs of primitive Pythagorean triangles sorted first on hypotenuse, then long leg.

7, 17, 23, 31, 41, 47, 49, 73, 71, 89, 79, 103, 113, 97, 119, 137, 119, 151, 127, 161, 193, 167, 161, 191, 217, 239, 217, 199, 257, 233, 263, 223, 289, 271, 311, 241, 281, 313, 329, 287, 343, 287, 329, 367, 391, 401, 353, 431, 409, 337, 383, 457, 359, 463, 479

Offset: 1

Author

Lekraj Beedassy, Jun 24 2006

Keywords

• nonn

Comments

The prime numbers congruent to +1 or -1 modulo 8 of this sequence appear exactly once. For a proof see the W. Lang link under A001132. - Wolfdieter Lang, Feb 17 2015

Links

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

Crossrefs

Cf. A120682, A058529, A118905, A198390, A001132, A046086, A046087.

Programs

Mathematica

A[s_Integer] := With[{s6 = StringPadLeft[ToString[s], 6, "0"]}, Cases[ Import["https://oeis.org/A" <> s6 <> "/b" <> s6 <> ".txt", "Table"], {, }][[All, 2]]];
A046086 = A@046086;
A046087 = A@046087;
a[n_] := A046087[[n]] + A046086[[n]];
a /@ Range[10000] (* Jean-François Alcover, Mar 07 2020 *)

Formula

a(n) = A046087(n) + A046086(n).

Extensions

Edited and corrected by Ray Chandler, Apr 10 2010