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A069429 Half the number of 3 X n binary arrays with no path of adjacent 1's or adjacent 0's from top row to bottom row. 93
3, 16, 84, 440, 2304, 12064, 63168, 330752, 1731840, 9068032, 47480832, 248612864, 1301753856, 6816071680, 35689414656, 186872201216, 978475548672, 5123364487168, 26826284728320, 140464250421248 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..20.

FORMULA

Empirical G.f.: x*(3-2*x)/(1-6*x+4*x^2). [Colin Barker, Feb 22 2012]

Empirical: a(n) = 3*A084326(n)-2*A084326(n-1). - R. J. Mathar, Nov 09 2018

CROSSREFS

Cf. 2 X n A000079, n X 1 A000225, vertical path of 1 A069361-A069395, vertical paths of 0+1 A069396-A069416, vertical path of 1 not 0 A069417-A069428, no vertical paths A069429-A069447, no horizontal or vertical paths A069448-A069452.

Sequence in context: A041707 A037584 A030983 * A275402 A026131 A026160

Adjacent sequences:  A069426 A069427 A069428 * A069430 A069431 A069432

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 22 2002

STATUS

approved

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Last modified November 19 06:26 EST 2019. Contains 329310 sequences. (Running on oeis4.)