A211427 Number of ordered triples (w,x,y) with all terms in {-n,...,0,...,n} and 3*w^2+x*y=0.

1, 5, 9, 21, 33, 37, 49, 53, 65, 77, 81, 85, 113, 117, 121, 133, 153, 157, 169, 173, 185, 197, 201, 205, 233, 253, 257, 301, 313, 317, 329, 333, 353, 365, 369, 373, 401, 405, 409, 421, 433, 437, 449, 453, 465, 477, 481, 485, 537, 573, 593, 605, 617

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[3 w^2 + x*y, {w, -n, n}, {x, -n, n}, {y, -n, n}]]
c[n_] := Count[t[n], 0]
t = Table[c[n], {n, 0, 90}]  (* A211427 *)
(t - 1)/4                    (* integers *)

Crossrefs

Cf. A211422.

Sequence in context: A169709 A269523 A319384 * A273410 A273486 A146867

Adjacent sequences: A211424 A211425 A211426 * A211428 A211429 A211430

Keyword

nonn

Author

Clark Kimberling, Apr 10 2012

Status

approved