A211430 - OEIS

%I #4 Apr 15 2012 21:22:45

%S 1,7,15,25,35,49,63,77,93,111,129,147,165,187,209,231,253,275,299,325,

%T 351,377,403,429,455,485,515,545,575,605,635,665,697,731,765,799,833,

%U 867,901,935,969,1007,1045,1083,1121,1159,1197,1235,1273,1311

%N Number of ordered triples (w,x,y) with all terms in {-n,...,0,...,n} and w^2+x+y=0.

%C For a guide to related sequences, see A211422.

%t t[n_] := t[n] = Flatten[Table[w^2 + x + y, {w, -n, n}, {x, -n, n}, {y, -n, n}]]

%t c[n_] := Count[t[n], 0]

%t t = Table[c[n], {n, 0, 70}]  (* A211430 *)

%t (t - 1)/2                    (* integers *)

%Y Cf. A211422.

%K nonn

%O 0,2

%A _Clark Kimberling_, Apr 10 2012