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A243600 Number of length n+2 0..3 arrays with no three elements in a row with pattern aba (with a!=b) and new values 0..3 introduced in 0..3 order. 1
4, 10, 28, 85, 269, 870, 2844, 9346, 30792, 101577, 335289, 1107066, 3655876, 12073706, 39875396, 131697309, 434963141, 1436579966, 4744692092, 15670638530, 51756579024, 170940329233, 564577491697, 1864672682930, 6158595344068 (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) = 5*a(n-1) - 5*a(n-2) - 3*a(n-3) + 3*a(n-4) + a(n-5).

Empirical g.f.: x*(4 - 10*x - 2*x^2 + 7*x^3 + 2*x^4) / ((1 - x)*(1 - x - x^2)*(1 - 3*x - x^2)). - Colin Barker, Nov 02 2018

EXAMPLE

Some solutions for n=5:

..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0

..1....0....1....0....0....1....1....1....0....0....0....1....1....1....1....1

..2....1....2....0....1....2....2....2....1....1....0....2....2....1....1....2

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

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

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

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

CROSSREFS

Column 3 of A243607.

Sequence in context: A083587 A228403 A061639 * A239577 A008995 A111236

Adjacent sequences:  A243597 A243598 A243599 * A243601 A243602 A243603

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jun 07 2014

STATUS

approved

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Last modified August 8 08:27 EDT 2020. Contains 336293 sequences. (Running on oeis4.)