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A163020 Number of nX3 binary arrays with all 1s connected and a path of 1s from left column to lower right corner 1
1, 12, 82, 469, 2502, 12966, 66325, 337222, 1709652, 8655795, 43794966, 221516992, 1120277983, 5665183308, 28647552996, 144861882889, 732516467528, 3704069018506, 18730095418683, 94711027286382, 478917748054834 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

R. H. Hardin, Table of n, a(n) for n=1..100

FORMULA

Empirical: a(n)= 10*a(n-1) -33*a(n-2) +45*a(n-3) -21*a(n-4) -15*a(n-5) +29*a(n-6) -9*a(n-7) -6*a(n-8) +a(n-9). G.f.: x*(-1-2*x+5*x^2+x^4+x^6)/((x-1) *(x^2+2*x-1) *(x^6-7*x^5+x^4+6*x^3-11*x^2+7* x-1) [From R. J. Mathar, Aug 11 2009]

CROSSREFS

Sequence in context: A069996 A183504 A194493 * A164300 A239180 A290715

Adjacent sequences:  A163017 A163018 A163019 * A163021 A163022 A163023

KEYWORD

nonn

AUTHOR

R. H. Hardin Jul 20 2009

STATUS

approved

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Last modified January 25 01:10 EST 2021. Contains 340414 sequences. (Running on oeis4.)