A163020 Number of nX3 binary arrays with all 1s connected and a path of 1s from left column to lower right corner.

1, 12, 82, 469, 2502, 12966, 66325, 337222, 1709652, 8655795, 43794966, 221516992, 1120277983, 5665183308, 28647552996, 144861882889, 732516467528, 3704069018506, 18730095418683, 94711027286382, 478917748054834, 2421704973341875, 12245640236904128

Offset

1,2

Links

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

Formula

From R. J. Mathar, Aug 11 2009: (Start)

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)). (End)

Crossrefs

Sequence in context: A069996 A183504 A194493 * A164300 A239180 A290715

Adjacent sequences: A163017 A163018 A163019 * A163021 A163022 A163023

Keyword

nonn,changed

Author

R. H. Hardin, Jul 20 2009

Status

approved