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A301843 Number of 3Xn 0..1 arrays with every element equal to 0, 1 or 2 horizontally or antidiagonally adjacent elements, with upper left element zero. 1
4, 32, 139, 678, 3182, 15199, 72514, 346244, 1653214, 7893443, 37688062, 179946317, 859175558, 4102237937, 19586633161, 93518758201, 446516665710, 2131948036306, 10179244758257, 48602040050313, 232056341426270, 1107981178164225 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 3 of A301841.

LINKS

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

FORMULA

Empirical: a(n) = 4*a(n-1) +3*a(n-2) +3*a(n-3) +2*a(n-4) -2*a(n-5) +2*a(n-6) -7*a(n-7) -3*a(n-8) +5*a(n-9) -4*a(n-10) -3*a(n-11) +a(n-12) for n>14

EXAMPLE

Some solutions for n=5

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

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

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

CROSSREFS

Cf. A301841.

Sequence in context: A088658 A088802 A123854 * A332430 A302070 A302267

Adjacent sequences:  A301840 A301841 A301842 * A301844 A301845 A301846

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 27 2018

STATUS

approved

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Last modified July 28 09:43 EDT 2021. Contains 346325 sequences. (Running on oeis4.)