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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.
1
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
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
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 11 2015
STATUS
approved