A020891 Ordered set of c + a - b as (a,b,c) runs through all primitive Pythagorean triples with a

4, 6, 8, 10, 10, 12, 14, 14, 16, 18, 18, 20, 22, 22, 24, 26, 26, 28, 28, 30, 30, 32, 34, 34, 36, 36, 38, 38, 40, 42, 42, 42, 44, 44, 46, 46, 48, 48, 50, 50, 52, 52, 54, 54, 56, 58, 58, 60, 60, 60, 62, 62, 64, 66, 66, 66, 66, 68, 68, 70, 70, 72, 74, 74, 76, 76, 78, 78, 78, 78, 80, 82, 82

Offset: 1

Author

Clark Kimberling

Keywords

• nonn

Links

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

Crossrefs

Cf. A020892.

Programs

Mathematica

pyth[nn_]:=Module[{tr={}}, Do[If[CoprimeQ[m,n]&&Mod[m+n,2]==1,AppendTo[tr,{m^2-n^2,2 m n,m^2+n^2}] ], {m,2,nn},{n,1,m-1}];tr]; Take[#[[3]]+#[[1]]-#[[2]]&/@(Sort/@pyth[50])//Sort,80] (* Harvey P. Dale, Jan 24 2025 *)

Formula

a(n) = 2*A020892(n).

Extensions

Extended and corrected by David W. Wilson

Offset corrected to 1 by Ray Chandler, Jan 23 2020