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A180763 Half the number of n X 3 binary arrays with each element equal to at least one neighbor. 1
1, 11, 63, 390, 2385, 14621, 89602, 549125, 3365327, 20624430, 126397089, 774626021, 4747304792, 29093913597, 178302394173, 1092728334730, 6696798543441, 41041409200977, 251522762447718, 1541460229095645 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 3 of A180771.

LINKS

R. H. Hardin, Table of n, a(n) for n=1..99

FORMULA

Empirical: a(n) = 5*a(n-1) + 8*a(n-2) - 5*a(n-3) - 10*a(n-4) - a(n-5) + 3*a(n-6) + 4*a(n-7) - 2*a(n-8).

Empirical g.f.: x*(1 - x)*(1 + 7*x + 7*x^2 - x^3 - 5*x^4 - 3*x^5 + 2*x^6) / (1 - 5*x - 8*x^2 + 5*x^3 + 10*x^4 + x^5 - 3*x^6 - 4*x^7 + 2*x^8). - Colin Barker, Mar 26 2018

CROSSREFS

Cf. A180771.

Sequence in context: A120723 A053367 A163706 * A285361 A237358 A250604

Adjacent sequences:  A180760 A180761 A180762 * A180764 A180765 A180766

KEYWORD

nonn

AUTHOR

R. H. Hardin, Sep 20 2010

STATUS

approved

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Last modified April 25 23:48 EDT 2019. Contains 322465 sequences. (Running on oeis4.)