A211428 Number of ordered triples (w,x,y) with all terms in {-n,...,0,...,n} and 2*w^2+3*x*y=0.

1, 5, 9, 21, 25, 29, 49, 53, 65, 77, 81, 85, 105, 109, 113, 125, 137, 141, 161, 165, 169, 181, 185, 189, 225, 237, 241, 269, 273, 277, 305, 309, 329, 341, 345, 349, 377, 381, 385, 397, 409, 413, 433, 437, 441, 453, 457, 461, 497, 517, 545, 557, 561

Offset

0,2

Comments

For a guide to related sequences, see A211422.

Links

Table of n, a(n) for n=0..52.

Mathematica

t[n_] := t[n] = Flatten[Table[2 w^2 + 3 x*y, {w, -n, n}, {x, -n, n}, {y, -n, n}]]
c[n_] := Count[t[n], 0]
t = Table[c[n], {n, 0, 70}]  (* A211428 *)
(t - 1)/4                    (* integers  *)

Crossrefs

Cf. A211422.

Sequence in context: A175364 A244642 A211424 * A160720 A147552 A299776

Adjacent sequences: A211425 A211426 A211427 * A211429 A211430 A211431

Keyword

nonn

Author

Clark Kimberling, Apr 10 2012

Status

approved