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A231538 Number of n X 2 0..1 arrays with no element less than a strict majority of its horizontal, vertical and antidiagonal neighbors. 1
2, 6, 20, 57, 164, 485, 1424, 4169, 12228, 35868, 105177, 308433, 904520, 2652574, 7778858, 22812126, 66898367, 196184665, 575326896, 1687191264, 4947820577, 14509871545, 42551335553, 124785126404, 365942162811, 1073154072467 (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) = 4*a(n-1) - 4*a(n-2) + 5*a(n-3) - 8*a(n-4) + 3*a(n-5) - 2*a(n-6) + a(n-7) - a(n-8).

Empirical g.f.: x*(2 - 2*x + 4*x^2 - 9*x^3 + 2*x^4 - x^5 + x^6 - x^7) / (1 - 4*x + 4*x^2 - 5*x^3 + 8*x^4 - 3*x^5 + 2*x^6 - x^7 + x^8). - Colin Barker, Sep 29 2018

EXAMPLE

Some solutions for n=7:

  0 1   1 0   1 1   0 1   1 1   1 0   0 1   0 0   0 0   1 0

  0 1   0 0   1 1   0 0   0 0   0 0   0 1   0 0   1 0   0 0

  0 0   0 1   0 0   1 0   0 0   0 1   0 1   0 0   0 0   1 1

  1 0   0 0   0 0   0 0   1 1   1 1   0 0   1 0   1 1   1 0

  0 1   0 1   1 0   0 1   1 1   1 1   1 0   1 0   1 1   0 0

  0 0   1 0   0 0   0 0   0 0   0 0   0 0   0 0   1 0   0 0

  0 0   0 0   0 1   0 0   0 0   0 0   0 1   0 1   0 0   0 0

CROSSREFS

Column 2 of A231544.

Sequence in context: A327414 A110295 A027294 * A082045 A005628 A000620

Adjacent sequences:  A231535 A231536 A231537 * A231539 A231540 A231541

KEYWORD

nonn

AUTHOR

R. H. Hardin, Nov 10 2013

STATUS

approved

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Last modified August 16 23:53 EDT 2022. Contains 356169 sequences. (Running on oeis4.)