A254971 Number of (n+2) X (1+2) 0..1 arrays with no 3 x 3 subblock diagonal sum 0 or 1 and no antidiagonal sum 0 or 1 and no row sum 0 and no column sum 0.

121, 310, 1008, 3241, 9961, 30529, 94351, 292130, 902991, 2789674, 8620990, 26645405, 82350302, 254503207, 786546750, 2430856047, 7512657571, 23218127711, 71756425958, 221765794486, 685375122700, 2118176184897, 6546298719088

Offset

1,1

Links

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

Formula

Empirical: a(n) = 2*a(n-1) + 2*a(n-2) + 3*a(n-3) + 5*a(n-4) - a(n-5) - 6*a(n-6) - 7*a(n-7) + 2*a(n-9) - a(n-10) for n>11.

Empirical g.f.: x*(121 + 68*x + 146*x^2 + 242*x^3 - 72*x^4 - 328*x^5 - 356*x^6 - 3*x^7 + 96*x^8 - 45*x^9 - 2*x^10) / ((1 + x)*(1 - 3*x + x^2 - 4*x^3 - x^4 + 2*x^5 + 4*x^6 + 3*x^7 - 3*x^8 + x^9)). - Colin Barker, Dec 18 2018

Example

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

Crossrefs

Column 1 of A254978.

Sequence in context: A106573 A084306 A254978 * A112075 A068872 A203856

Adjacent sequences: A254968 A254969 A254970 * A254972 A254973 A254974

Keyword

nonn

Author

R. H. Hardin, Feb 11 2015

Status

approved