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A249285 Number of length n+3 0..3 arrays with no four consecutive terms having the sum of any three elements equal to three times the fourth. 1
204, 660, 2144, 6960, 22572, 73204, 237480, 770416, 2499164, 8107012, 26298608, 85311248, 276744204, 897739412, 2912207432, 9447011744, 30645489228, 99411957620, 322485877472, 1046123080816, 3393554802188, 11008469603188 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = 2*a(n-1) + 2*a(n-2) + 4*a(n-3) + 8*a(n-4) + 4*a(n-5) - 8*a(n-6) - 2*a(n-7) + 3*a(n-8).

Empirical g.f.: 4*x*(51 + 63*x + 104*x^2 + 134*x^3 + 23*x^4 - 133*x^5 - 18*x^6 + 48*x^7) / (1 - 2*x - 2*x^2 - 4*x^3 - 8*x^4 - 4*x^5 + 8*x^6 + 2*x^7 - 3*x^8). - Colin Barker, Nov 09 2018

EXAMPLE

Some solutions for n=6:

  3  0  3  2  1  1  3  0  0  0  3  3  1  2  0  2

  3  1  3  2  0  1  1  0  1  2  1  3  0  3  2  2

  1  1  2  1  3  1  3  2  0  2  0  1  1  2  2  1

  2  1  3  1  3  0  1  0  2  0  1  1  1  2  0  0

  0  0  2  3  1  0  3  2  3  3  3  2  3  0  2  0

  2  3  0  3  1  1  0  2  0  1  1  2  0  0  0  1

  2  3  1  3  3  0  3  0  1  3  0  0  2  2  2  1

  3  0  3  1  3  1  3  3  1  1  2  1  0  3  1  3

  3  1  1  1  2  0  3  2  0  2  0  0  0  2  2  0

CROSSREFS

Column 3 of A249290.

Sequence in context: A163393 A245468 A154518 * A292346 A234796 A234789

Adjacent sequences:  A249282 A249283 A249284 * A249286 A249287 A249288

KEYWORD

nonn

AUTHOR

R. H. Hardin, Oct 24 2014

STATUS

approved

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Last modified October 20 10:32 EDT 2019. Contains 328257 sequences. (Running on oeis4.)