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A180762 Half the number of nX2 binary arrays with each element equal to at least one neighbor 11
1, 3, 11, 34, 111, 361, 1172, 3809, 12377, 40218, 130687, 424661, 1379916, 4483973, 14570461, 47346034, 153848731, 499924281, 1624480652, 5278674169, 17152805697, 55737242698, 181115572487, 588526611821, 1912389796556, 6214221516093 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 2 of A180771

LINKS

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

FORMULA

Empirical: a(n) = 3*a(n-1) + a(n-2) - 2*a(n-4).

Empirical G.f.: x*(1-x)*(1+x+2*x^2)/(1-3*x-x^2+2*x^4). [Colin Barker, Feb 22 2012]

CROSSREFS

Sequence in context: A084266 A052471 A037496 * A134326 A295546 A094308

Adjacent sequences:  A180759 A180760 A180761 * A180763 A180764 A180765

KEYWORD

nonn

AUTHOR

R. H. Hardin Sep 20 2010

STATUS

approved

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Last modified October 15 01:40 EDT 2019. Contains 328025 sequences. (Running on oeis4.)