A212060 - OEIS

%I #10 Oct 23 2019 16:44:10

%S 0,0,3,6,15,18,28,34,43,46,64,67,76,85,100,103,121,124,142,151,160,

%T 163,193,199,208,218,236,239,266,269,290,299,308,317,353,356,365,374,

%U 404,407,434,437,455,473,482,485,530,536,554,563,581,584,614,623

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

%C For a guide to related sequences, see A211795.

%H Robert Israel, <a href="/A212060/b212060.txt">Table of n, a(n) for n = 0..10000</a>

%p N:= 100:

%p A:= Vector(N):

%p for x from 1 to N do

%p   for y from 1 to min(N,floor((N+2)/x)) do

%p     for z from max(1,ceil(3/(x*y))) to min(N,floor((N+2)/(x*y))) do

%p   w:=max(x,y,z,x*y*z-2);

%p   A[w]:= A[w]+1;

%p od od od:

%p B:= ListTools:-PartialSums(convert(A,list)):

%p 0,op(B); # _Robert Israel_, Oct 23 2019

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

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

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

%t Map[t[#] &, Range[0, 60]] (* A212060 *)

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

%Y Cf. A211795.

%K nonn

%O 0,3

%A _Clark Kimberling_, Apr 30 2012