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A245991 Number of length n+2 0..4 arrays with no pair in any consecutive three terms totalling exactly 4. 1
64, 208, 676, 2196, 7132, 23168, 75260, 244464, 794096, 2579500, 8379052, 27217860, 88412560, 287192948, 932896352, 3030352272, 9843575108, 31975148500, 103865731612, 337389844512, 1095952482460, 3560011839440, 11564081956784 (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) + a(n-2) + 9*a(n-3) + 3*a(n-4).

Empirical g.f.: 4*x*(16 + 20*x + 49*x^2 + 15*x^3) / (1 - 2*x - x^2 - 9*x^3 - 3*x^4). - Colin Barker, Nov 05 2018

EXAMPLE

Some solutions for n=7:

  3  3  4  0  2  2  3  2  2  3  4  3  4  0  4  0

  4  4  1  3  1  1  4  3  4  2  2  0  1  3  2  1

  4  4  1  0  1  1  3  4  4  3  4  2  2  2  1  1

  4  2  2  2  0  4  4  3  2  3  3  0  0  3  4  2

  3  4  0  0  2  2  3  3  1  0  2  1  3  4  4  4

  3  3  0  3  0  1  2  3  4  0  4  2  3  3  3  4

  2  3  0  0  1  1  0  0  2  2  1  1  0  2  4  4

  4  0  3  0  1  2  3  0  1  3  2  4  2  3  4  4

  4  0  2  1  1  4  0  3  0  4  1  1  1  0  2  4

CROSSREFS

Column 4 of A245995.

Sequence in context: A250135 A273321 A091077 * A186637 A295021 A194932

Adjacent sequences:  A245988 A245989 A245990 * A245992 A245993 A245994

KEYWORD

nonn

AUTHOR

R. H. Hardin, Aug 09 2014

STATUS

approved

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Last modified August 26 00:35 EDT 2019. Contains 326324 sequences. (Running on oeis4.)