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A265993 Number of 3 X n integer arrays with each element equal to the number of horizontal and antidiagonal neighbors not equal to itself. 1
1, 2, 6, 2, 3, 9, 9, 16, 27, 35, 55, 105, 145, 202, 369, 589, 857, 1371, 2229, 3444, 5411, 8585, 13399, 21170, 33573, 52488, 82413, 130606, 205585, 322481, 508515, 801862, 1261277, 1985864, 3128187, 4924251, 7755005, 12214150, 19226531, 30273410 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

FORMULA

Empirical: a(n) = a(n-1) + 2*a(n-3) + a(n-4) - 3*a(n-5) - a(n-6) - a(n-7) + a(n-8) + 7*a(n-9) - 2*a(n-10) - 4*a(n-11) + 9*a(n-14) + 3*a(n-15) - 8*a(n-16) - 4*a(n-17) for n>20.

Empirical g.f.: x*(1 + x + 4*x^2 - 6*x^3 - 4*x^4 - 5*x^5 - 3*x^6 + 20*x^7 + 3*x^8 - 11*x^9 - 7*x^10 - 17*x^11 + 12*x^12 + 16*x^13 - 17*x^14 - 18*x^15 - 13*x^16 - 3*x^17 + 8*x^18 + 4*x^19) / ((1 - x)*(1 + x^2 - x^3 - x^4 + 3*x^7 + 2*x^8)*(1 - x^2 - x^3 - x^4 - 3*x^7 - 2*x^8)). - Colin Barker, Jan 09 2019

EXAMPLE

Some solutions for n=6:

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

..1..1..1..1..1..1....2..3..3..4..1..1....1..1..4..1..1..1....2..1..1..1..1..1

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

CROSSREFS

Row 3 of A265991.

Sequence in context: A316259 A057892 A334188 * A115009 A151944 A073094

Adjacent sequences:  A265990 A265991 A265992 * A265994 A265995 A265996

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 19 2015

STATUS

approved

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Last modified April 11 07:53 EDT 2021. Contains 342886 sequences. (Running on oeis4.)