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A212050
Number of (w,x,y,z) with all terms in {1,...,n} and 2w*x=5*y*z.
2
0, 0, 0, 0, 0, 20, 32, 36, 46, 54, 118, 126, 162, 170, 194, 316, 358, 370, 430, 442, 614, 666, 714, 730, 840, 1064, 1124, 1184, 1276, 1296, 1686, 1710, 1824, 1908, 1980, 2320, 2524, 2552, 2636, 2732, 3202, 3234, 3470, 3502, 3658, 4222, 4330
OFFSET
0,6
COMMENTS
Each term is divisible by 2. See A211795 for a guide to related sequences.
MATHEMATICA
t = Compile[{{n, _Integer}}, Module[{s = 0},
(Do[If[2 w*x == 5 y*z, s = s + 1],
{w, 1, #}, {x, 1, #}, {y, 1, #}, {z, 1, #}] &[n]; s)]];
Map[t[#] &, Range[0, 50]] (* A212050 *)
%/2 (* integers *)
(* Peter J. C. Moses, Apr 13 2012 *)
CROSSREFS
Cf. A211795.
Sequence in context: A077343 A218793 A116131 * A075035 A032352 A333729
KEYWORD
nonn
AUTHOR
Clark Kimberling, Apr 29 2012
STATUS
approved