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A231020 Number of (n+3)X(2+3) 0..3 black square subarrays x(i,j) with each element diagonally or antidiagonally next to at least one element with value (x(i,j)+1) mod 4, and upper left element zero 1
16, 242, 724, 10534, 28128, 419878, 1144652, 16946918, 46058744, 683352174, 1857863476, 27552792942, 74908095984, 1110991043910, 3020446141788, 44796988899478, 121789649054696, 1806294227298910, 4910772371719684 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A231023

LINKS

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

FORMULA

Empirical: a(n) = 31*a(n-2) +375*a(n-4) +233*a(n-6) -7946*a(n-8) -884*a(n-10) -16296*a(n-12) -203520*a(n-14) +53120*a(n-16)

EXAMPLE

Some solutions for n=2

..x..0..x..2..x....x..0..x..2..x....x..0..x..2..x....x..0..x..0..x

..3..x..1..x..3....1..x..3..x..1....1..x..3..x..3....3..x..1..x..3

..x..2..x..0..x....x..2..x..2..x....x..2..x..0..x....x..0..x..2..x

..1..x..3..x..3....3..x..1..x..3....3..x..1..x..3....3..x..1..x..3

..x..0..x..2..x....x..0..x..0..x....x..0..x..0..x....x..0..x..0..x

CROSSREFS

Sequence in context: A175720 A135518 A179092 * A274856 A064232 A074153

Adjacent sequences:  A231017 A231018 A231019 * A231021 A231022 A231023

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 03 2013

STATUS

approved

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Last modified May 22 15:13 EDT 2019. Contains 323480 sequences. (Running on oeis4.)