A252221 Number of (n+2) X (1+2) 0..2 arrays with every 3 X 3 subblock row and column sum 2 3 or 4 and every diagonal and antidiagonal sum not 2 3 or 4.

228, 368, 812, 1442, 2458, 4738, 9922, 20070, 38774, 75106, 148914, 296946, 586790, 1153474, 2273494, 4495766, 8887778, 17542298, 34612226, 68336662, 134968250, 266516414, 526161790, 1038785394, 2051072242, 4049909170, 7996310710

Offset

1,1

Links

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

Formula

Empirical: a(n) = 2*a(n-1) - a(n-2) + a(n-3) + 3*a(n-4) - 2*a(n-5) - 2*a(n-7) for n>10.

Empirical g.f.: 2*x*(114 - 44*x + 152*x^2 - 21*x^3 - 333*x^4 - 98*x^5 - 119*x^6 + 130*x^7 + 32*x^8 + 16*x^9) / ((1 - x)*(1 - x - x^3 - 4*x^4 - 2*x^5 - 2*x^6)). - Colin Barker, Dec 02 2018

Example

Some solutions for n=4:
..1..1..1....1..0..2....0..1..1....0..1..1....1..2..1....1..0..2....1..0..1
..0..2..1....1..2..0....2..0..2....2..0..1....0..2..1....1..2..0....2..0..1
..2..0..2....1..0..2....0..2..0....0..2..1....2..0..2....2..0..2....0..2..0
..0..2..0....1..2..0....2..0..2....2..0..2....0..2..0....0..2..0....2..0..1
..1..0..1....1..0..2....1..2..1....0..2..0....1..0..1....2..0..1....0..2..1
..1..0..1....1..2..0....1..1..1....1..1..1....1..1..1....0..1..1....2..0..1

Crossrefs

Column 1 of A252228.

Sequence in context: A258550 A335269 A252228 * A154519 A128808 A043411

Adjacent sequences: A252218 A252219 A252220 * A252222 A252223 A252224

Keyword

nonn

Author

R. H. Hardin, Dec 15 2014

Status

approved