A212111 - OEIS

%I #5 Dec 04 2016 19:46:29

%S 0,0,5,48,180,481,1034,1986,3441,5602,8623,12755,18126,25165,33951,

%T 44936,58367,74638,93934,116987,143760,175126,211253,252782,299884,

%U 353673,414098,482057,557997,642810,736317,840479,954638,1080451

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

%C A212111(n)+A212132(n)=n^4.  For a guide to related sequences, see A211795.

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

%t (Do[If[w*x + y*z < n^2, s = s + 1],

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

%t Map[t[#] &, Range[0, 60]]   (* A212111 *)

%t (* _Peter J. C. Moses_, Apr 13 2012 *)

%Y Cf. A211795.

%K nonn

%O 0,3

%A _Clark Kimberling_, May 07 2012