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A153366
Number of zig-zag paths from top to bottom of a rectangle of width 9 with 2n-1 rows whose color is that of the top right corner.
5
5, 16, 56, 200, 720, 2600, 9400, 34000, 123000, 445000, 1610000, 5825000, 21075000, 76250000, 275875000, 998125000, 3611250000, 13065625000, 47271875000, 171031250000, 618796875000, 2238828125000, 8100156250000, 29306640625000
OFFSET
1,1
FORMULA
Empirical G.f.: x*(5-9*x+x^2)/(1-5*x+5*x^2). - Colin Barker, Jan 04 2012
KEYWORD
nonn,easy
AUTHOR
Joseph Myers, Dec 24 2008
STATUS
approved