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A153364
Number of zig-zag paths from top to bottom of a rectangle of width 9 with n rows whose color is not that of the top right corner
5
4, 8, 14, 28, 50, 100, 180, 360, 650, 1300, 2350, 4700, 8500, 17000, 30750, 61500, 111250, 222500, 402500, 805000, 1456250, 2912500, 5268750, 10537500, 19062500, 38125000, 68968750, 137937500, 249531250, 499062500, 902812500, 1805625000
OFFSET
1,1
FORMULA
Empirical G.f.: x*(4+8*x-6*x^2-12*x^3)/(1-5*x^2+5*x^4). - Colin Barker, Jan 04 2012
KEYWORD
easy,nonn
AUTHOR
Joseph Myers, Dec 24 2008
STATUS
approved