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

%I #8 Oct 21 2022 19:46:09

%S 0,0,0,4,12,15,21,36,45,46,64,76,88,91,114,120,144,156,153,186,204,

%T 201,235,235,268,271,289,316,334,340,361,382,408,408,444,465,465,489,

%U 519,525,576,573,589,616,652,640,664,709,736,748,760,778,826,808

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

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

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

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

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

%t Map[t[#] &, Range[0, 60]] (* A212245 *)

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

%Y Cf. A211795.

%K nonn

%O 0,4

%A _Clark Kimberling_, May 08 2012