A381711 a(n) = A379597(n) - A381710(n).

1, 3, 7, 13, 25, 41, 65, 93, 133, 177, 245, 305, 397, 489, 609, 725, 893, 1029, 1241, 1425, 1665, 1889, 2209, 2457, 2821, 3145, 3549, 3913, 4429, 4805, 5397, 5885, 6493, 7045, 7781, 8341, 9185, 9881, 10745, 11489, 12545, 13297, 14453, 15385, 16497, 17517, 18917

Offset: 1

Author

Felix Huber, Mar 08 2025

Keywords

• nonn

Comments

a(n) is odd.

Links

• Felix Huber, Table of n, a(n) for n = 1..4051
• Eric Weisstein's World of Mathematics, Quadratic Equation

Crossrefs

Cf. A067274, A091626, A091627, A364384, A364385, A365876, A365877, A379597, A381710.

Programs

Maple

A381711:=proc(n)
   option remember;
   local a,u,v,w;
   if n=1 then
      1
   else
      a:=0;
      for u to n-1 do
         for v from 0 to n-u do
            w:=n-u-v;
            if igcd(u,v,w)=1 and v<>0 then
               if w=0 or w=v^2/(4*u) then
                  a:=a+2
               elif wA381711(n),n=1..47);

Formula

a(n) = A379597(n) - A381710(n).