A212065 Number of (w,x,y,z) with all terms in {1,...,n} and w^2<=x*y*z.

0, 1, 12, 57, 185, 459, 974, 1830, 3168, 5158, 7957, 11766, 16830, 23378, 31689, 42041, 54774, 70218, 88757, 110720, 136558, 166715, 201620, 241761, 287646, 339854, 398829, 465198, 539557, 622513, 714762, 816892, 929637, 1053742

Offset: 0

Author

Clark Kimberling, Apr 30 2012

Keywords

• nonn

Comments

a(n)+A212066(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]] (* A212065 *)
(* Peter J. C. Moses, Apr 13 2012 *)