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A213497
Number of (w,x,y) with all terms in {0,...,n} and w = min(|w-x|, |x-y|).
2
1, 4, 10, 17, 29, 40, 57, 73, 95, 115, 143, 167, 200, 229, 267, 300, 344, 381, 430, 472, 526, 572, 632, 682, 747, 802, 872, 931, 1007, 1070, 1151, 1219, 1305, 1377, 1469, 1545, 1642, 1723, 1825, 1910, 2018, 2107, 2220, 2314, 2432, 2530, 2654
OFFSET
0,2
COMMENTS
For a guide to related sequences, see A212959.
FORMULA
a(n) = 2*a(n-2) + a(n-3) - a(n-4) - 2*a(n-5) + a(n-7).
G.f.: (1 + 4*x + 8*x^2 + 8*x^3 + 6*x^4 + 2*x^5)/((1 - x)^3 (1 + x)^2 (1 + x + x^2)).
a(n) = (n+1)^3 - A213499(n).
MATHEMATICA
t = Compile[{{n, _Integer}}, Module[{s = 0},
(Do[If[w == Min[Abs[w - x], Abs[x - y]], s = s + 1],
{w, 0, n}, {x, 0, n}, {y, 0, n}]; s)]];
m = Map[t[#] &, Range[0, 60]]
CROSSREFS
Sequence in context: A341772 A301195 A008022 * A339576 A047699 A167209
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jun 14 2012
STATUS
approved