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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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified December 7 13:08 EST 2021. Contains 349581 sequences. (Running on oeis4.)