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A212143 Number of (w,x,y,z) with all terms in {1,...,n} and w <= (geometric mean of x,y,z). 2
0, 1, 9, 39, 121, 285, 579, 1069, 1815, 2904, 4396, 6417, 9060, 12448, 16704, 21969, 28414, 36153, 45393, 56272, 69012, 83814, 100888, 120447, 142692, 167944, 196341, 228231, 263815, 303435, 347295, 395794, 449244, 507867, 572014 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

A212143(n)+A212144(n)=n^4.  For a guide to related sequences, see A211795.

LINKS

Table of n, a(n) for n=0..34.

MATHEMATICA

t = Compile[{{n, _Integer}}, Module[{s = 0},

(Do[If[w^3 <= x*y*z, s = s + 1],

{w, 1, #}, {x, 1, #}, {y, 1, #}, {z, 1, #}] &[n]; s)]];

Map[t[#] &, Range[0, 50]] (* A212143  *)

(* Peter J. C. Moses, Apr 13 2012 *)

CROSSREFS

Cf. A211795.

Sequence in context: A139594 A034263 A060929 * A294845 A124851 A317019

Adjacent sequences:  A212140 A212141 A212142 * A212144 A212145 A212146

KEYWORD

nonn

AUTHOR

Clark Kimberling, May 06 2012

STATUS

approved

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Last modified January 27 17:58 EST 2020. Contains 331296 sequences. (Running on oeis4.)