A153366 Number of zig-zag paths from top to bottom of a rectangle of width 9 with 2*n-1 rows whose color is that of the top right corner.
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
Links
- Joseph Myers, BMO 2008--2009 Round 1 Problem 1---Generalisation
Formula
Empirical G.f.: x*(5-9*x+x^2)/(1-5*x+5*x^2). - Colin Barker, Jan 04 2012