A212065 - OEIS

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

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OFFSET

0,3

COMMENTS

a(n)+A212066(n)=n^4. For a guide to related sequences, see A211795.

LINKS

Table of n, a(n) for n=0..33.

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 *)

CROSSREFS

Cf. A211795.

Sequence in context: A212134 A071270 A051877 * A121693 A190297 A072259

Adjacent sequences: A212062 A212063 A212064 * A212066 A212067 A212068

KEYWORD

nonn

AUTHOR

Clark Kimberling, Apr 30 2012

STATUS

approved