OFFSET
1,3
COMMENTS
For a guide to related sequences, see A210000.
LINKS
Chai Wah Wu, Table of n, a(n) for n = 1..1000
MATHEMATICA
a = 1; b = n; z1 = 40;
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]
d[n_, m_] := d[n, m] = Sum[c[n, k], {k, 0, m}]
Table[d[n, n^2] - d[n, 2 n - 1], {n, 1, z1}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Mar 31 2012
STATUS
approved