OFFSET
1,2
COMMENTS
For a guide to related sequences, see A210000.
LINKS
Chai Wah Wu, Table of n, a(n) for n = 1..3000
EXAMPLE
a(2) counts these 2 matrices:
2 1.....2 2
2 2.....1 2
MATHEMATICA
a = 1; b = n; z1 = 45;
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], {n, 1, z1}] (* A211053 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Mar 31 2012
STATUS
approved