A257440 Number of (n+2) X (1+2) 0..1 arrays with no 3 x 3 subblock diagonal sum 0 and no antidiagonal sum 3 and no row sum 1 and no column sum 1.

30, 36, 39, 49, 65, 90, 128, 186, 269, 392, 573, 836, 1223, 1791, 2621, 3839, 5625, 8240, 12074, 17694, 25928, 37997, 55686, 81608, 119600, 175281, 256883, 376478, 551754, 808631, 1185104, 1736853, 2545478, 3730577, 5467425, 8012897, 11743469

Offset

1,1

Links

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

Formula

Empirical: a(n) = a(n-1) + 2*a(n-3) - a(n-4) - a(n-6) for n>12.

Empirical g.f.: x*(30 + 6*x + 3*x^2 - 50*x^3 - 26*x^4 - 17*x^5 + 9*x^6 + 13*x^7 + 7*x^8 + 6*x^9 + 2*x^10 + x^11) / ((1 - x)*(1 + x + x^2)*(1 - x - x^3)). - Colin Barker, Dec 21 2018

Example

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

Crossrefs

Column 1 of A257447.

Sequence in context: A368496 A138689 A257447 * A114840 A284787 A214408

Adjacent sequences: A257437 A257438 A257439 * A257441 A257442 A257443

Keyword

nonn

Author

R. H. Hardin, Apr 23 2015

Status

approved