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A230931 Number of black-square subarrays of (n+2)X(4+2) 0..3 arrays x(i,j) with each element diagonally or antidiagonally next to at least one element with value (x(i,j)+1) mod 4, no adjacent elements equal, and upper left element zero 2
8, 48, 232, 1242, 6896, 37984, 208172, 1142054, 6269172, 34409586, 188850410, 1036485334, 5688689754, 31221981876, 171359511448, 940494098820, 5161833500756, 28330347062146, 155489043088298, 853390273229980 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 4 of A230935

LINKS

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

FORMULA

Empirical: a(n) = 5*a(n-1) +a(n-2) +11*a(n-3) -a(n-4) -33*a(n-5) -82*a(n-6) +a(n-7) -33*a(n-8) +71*a(n-9) +125*a(n-10) +117*a(n-11) +140*a(n-12) +66*a(n-13) +35*a(n-14) +2*a(n-15) -4*a(n-16) -4*a(n-17)

EXAMPLE

Some solutions for n=4

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

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

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

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

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

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

CROSSREFS

Sequence in context: A271061 A211012 A081084 * A073390 A069021 A079763

Adjacent sequences:  A230928 A230929 A230930 * A230932 A230933 A230934

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 01 2013

STATUS

approved

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Last modified December 8 12:28 EST 2021. Contains 349596 sequences. (Running on oeis4.)