OFFSET
0,2
COMMENTS
For a guide to related sequences, see A210000.
LINKS
Chai Wah Wu, Table of n, a(n) for n = 0..3000
MATHEMATICA
a = -n; b = n; z1 = 35;
t[n_] := t[n] = Flatten[Table[w*z - x*y, {w, a, b}, {x, a, b}, {y, a, b}, {z, a, b}]]
c[n_, k_] := c[n, k] = Count[t[n], k]
Table[c[n, n + 1], {n, 0, z1}] (* A211142 *)
%/4 (* integers *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Apr 03 2012
STATUS
approved