OFFSET
0,3
COMMENTS
Each term is divisible by 2. See A211795 for a guide to related sequences.
LINKS
Bo Gyu Jeong, Table of n, a(n) for n = 0..200
EXAMPLE
a(2) counts these four 4-tuples: (1,2,1,1), (2,1,1,1), (2,2,1,2), (2,2,2,1).
MATHEMATICA
t = Compile[{{n, _Integer}}, Module[{s = 0},
(Do[If[w*x == 2 y*z, s = s + 1],
{w, 1, #}, {x, 1, #}, {y, 1, #}, {z, 1, #}] &[n]; s)]];
Map[t[#] &, Range[0, 60]] (* A212019 *)
%/2 (* integers *)
(* Peter J. C. Moses, Apr 13 2012 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Apr 28 2012
STATUS
approved