A212064 Number of (w,x,y,z) with all terms in {1,...,n} and w^2>=x*y*z.

0, 1, 8, 31, 87, 185, 353, 605, 978, 1471, 2123, 2958, 4028, 5308, 6864, 8733, 10947, 13491, 16452, 19837, 23711, 28047, 32929, 38376, 44498, 51181, 58569, 66699, 75588, 85260, 95808, 107202, 119569, 132821, 147102, 162427, 178898

Offset: 0

Author

Clark Kimberling, Apr 30 2012

Keywords

• nonn

Comments

a(n)+A212063(n)=n^4. For a guide to related sequences, see A211795.

Crossrefs

Cf. A211795.

Programs

Mathematica

t = Compile[{{n, _Integer}}, Module[{s = 0},
(Do[If[w^2 >= x*y*z, s = s + 1],
{w, 1, #}, {x, 1, #}, {y, 1, #}, {z, 1, #}] &[n]; s)]];
Map[t[#] &, Range[0, 50]] (* A212064 *)
(* Peter J. C. Moses, Apr 13 2012 *)