cp's OEIS Frontend

A211920 Number of (w,x,y,z) with all terms in {1,...,n} and 2*w*x<3*y*z.

%I A211920 #12 Dec 04 2016 19:46:28
%S A211920 0,1,11,50,160,387,792,1480,2511,4001,6104,8943,12623,17396,23374,
%T A211920 30765,39803,50707,63656,79050,96985,117795,141871,169444,200754,
%U A211920 236327,276397,321322,371547,427471,489342,557906,633285,716040,806754
%N A211920 Number of (w,x,y,z) with all terms in {1,...,n} and 2*w*x<3*y*z.
%C A211920 a(n)+A211923(n)=n^4.
%C A211920 See A211795 for a guide to related sequences.
%t A211920 t = Compile[{{n, _Integer}}, Module[{s = 0},
%t A211920 (Do[If[2 w*x < 3 y*z, s = s + 1],
%t A211920 {w, 1, #}, {x, 1, #}, {y, 1, #}, {z, 1, #}] &[n]; s)]];
%t A211920 Map[t[#] &, Range[0, 40]] (* A211920 *)
%t A211920 (* _Peter J. C. Moses_, Apr 13 2012 *)
%Y A211920 Cf. A211795.
%K A211920 nonn
%O A211920 0,3
%A A211920 _Clark Kimberling_, Apr 28 2012