A208109 - OEIS

A208109

Number of 4 X n 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 1 1 and 1 1 0 vertically.

9, 81, 171, 361, 1805, 9025, 25555, 72361, 292941, 1185921, 3801699, 12187081, 45351581, 168766081, 570110035, 1925893225, 6923341485, 24888533121, 85943617731, 296775442441, 1051712556989, 3727058052481, 12988702493491

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OFFSET

1,1

COMMENTS

Row 4 of A208108.

LINKS

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

FORMULA

Empirical: a(n) = 2*a(n-1) + 8*a(n-3) + 61*a(n-4) - 66*a(n-5) - 48*a(n-6) - 252*a(n-8) + 216*a(n-9).

Empirical g.f.: x*(9 + 63*x + 9*x^2 - 53*x^3 - 114*x^4 - 300*x^5 - 36*x^6 - 36*x^7 + 216*x^8) / ((1 - 2*x - 7*x^2 + 6*x^3)*(1 + 7*x^2 - 12*x^4 - 36*x^6)). - Colin Barker, Jun 28 2018

EXAMPLE

Some solutions for n=8:

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

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

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

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

CROSSREFS

Cf. A208108.

Sequence in context: A208104 A207725 A044260 * A208841 A207489 A207886

Adjacent sequences: A208106 A208107 A208108 * A208110 A208111 A208112

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 23 2012

STATUS

approved