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

8, 48, 232, 1242, 6896, 37984, 208172, 1142054, 6269172, 34409586, 188850410, 1036485334, 5688689754, 31221981876, 171359511448, 940494098820, 5161833500756, 28330347062146, 155489043088298, 853390273229980

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