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A212965 Number of (w,x,y) with all terms in {0,...,n} and w=range{w,x,y}. 4
1, 4, 12, 21, 37, 52, 76, 97, 129, 156, 196, 229, 277, 316, 372, 417, 481, 532, 604, 661, 741, 804, 892, 961, 1057, 1132, 1236, 1317, 1429, 1516, 1636, 1729, 1857, 1956, 2092, 2197, 2341, 2452, 2604, 2721, 2881, 3004, 3172, 3301, 3477, 3612 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

For a guide to related sequences, see A212959.

LINKS

Table of n, a(n) for n=0..45.

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

FORMULA

a(n) = (14*n*(n+1) + (2*n+1)*(-1)^n + 7)/8.

a(n) = a(n-1)+2*a(n-2)-2*a(n-3)-a(n-4)+a(n-5).

G.f.: f(x)/g(x), where f(x)=1 + 3*x + 6*x^2 + 3*x^3 + x^4 and g(x)=((1+x)^2)(1-x)^3.

MATHEMATICA

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

(Do[If[w == Max[w, x, y] - Min[w, x, y], s = s + 1],

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

Map[t[#] &, Range[0, 50]]   (* A212965 *)

CROSSREFS

Cf. A212959.

Sequence in context: A008167 A008150 A301234 * A301226 A008200 A008198

Adjacent sequences:  A212962 A212963 A212964 * A212966 A212967 A212968

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling, Jun 02 2012

STATUS

approved

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Last modified September 18 12:35 EDT 2021. Contains 347527 sequences. (Running on oeis4.)