A212752 - OEIS

A212752

Number of (w,x,y,z) with all terms in {0,...,n} and at least one of these conditions holds: w<R, x<R, y<R, z>R, where R=max{w,x,y,z}-min{w,x,y,z}.

0, 14, 71, 238, 580, 1224, 2265, 3896, 6236, 9550, 13975, 19854, 27336, 36848, 48545, 62944, 80200, 100926, 125271, 153950, 187100, 225544, 269401, 319608, 376260, 440414, 512135, 592606, 681856, 781200, 890625, 1011584, 1144016

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OFFSET

0,2

COMMENTS

For a guide to related sequences, see A211795.

LINKS

Table of n, a(n) for n=0..32.

Index entries for linear recurrences with constant coefficients, signature (2,2,-6,0,6,-2,-2,1).

FORMULA

a(n)=2*a(n-1)+2*a(n-2)-6*a(n-3)+6*a(n-5)-2*a(n-6)-2*a(n-7)+a(n-8).

G.f.: -x*(14+43*x+68*x^2+46*x^3+14*x^4+x^5) / ( (1+x)^3*(x-1)^5 )

MATHEMATICA

t = Compile[{{n, _Integer}},

Module[{s = 0}, (Do[If[(w < # || x < # || y < # || z > #) &[Max[w, x, y, z] - Min[w, x, y, z]], s++],

{w, 0, n}, {x, 0, n}, {y, 0, n}, {z, 0, n}]; s)]];

Map[t[#] &, Range[0, 40]] (* A212752 *)

(* Peter J. C. Moses, May 24 2012 *)

CROSSREFS

Cf. A211795.

Sequence in context: A352869 A212572 A186707 * A074086 A205335 A212750

Adjacent sequences: A212749 A212750 A212751 * A212753 A212754 A212755

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling, May 27 2012

STATUS

approved