A284076 - OEIS

A284076

Number of 2Xn 0..1 arrays with no 1 equal to more than three of its horizontal, diagonal and antidiagonal neighbors, with the exception of exactly two elements.

0, 0, 1, 6, 33, 176, 858, 4000, 18298, 82176, 363027, 1584090, 6844659, 29327056, 124752876, 527398452, 2217568396, 9279837664, 38668567653, 160517532910, 664042452165, 2738524464624, 11261702650622, 46191451640392

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OFFSET

1,4

COMMENTS

Row 2 of A284075.

LINKS

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

FORMULA

Empirical: a(n) = 9*a(n-1) -24*a(n-2) +30*a(n-3) -84*a(n-4) +48*a(n-5) +106*a(n-6) +318*a(n-7) +813*a(n-8) +919*a(n-9) +990*a(n-10) +756*a(n-11) +216*a(n-12).

Empirical g.f.: x^2*(-1 +3*x -3*x^2 +7*x^3 +30*x^4 +32*x^5 +12*x^6)/ (6*x^4+7*x^3+x^2+3*x-1)^3 . - R. J. Mathar, Mar 21 2017

EXAMPLE

Some solutions for n=4

..1..1..1..1. .0..1..1..1. .1..1..1..0. .1..1..1..1. .1..1..1..0

..0..1..1..1. .1..1..1..1. .1..1..1..1. .1..1..1..0. .1..1..1..0

CROSSREFS

Cf. A284075.

Sequence in context: A086091 A081893 A106850 * A094165 A111994 A092851

Adjacent sequences: A284073 A284074 A284075 * A284077 A284078 A284079

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 19 2017

STATUS

approved