A153365 Number of zig-zag paths from top to bottom of a rectangle of width 9 with 2*n rows whose color is that of the top right corner.

8, 28, 100, 360, 1300, 4700, 17000, 61500, 222500, 805000, 2912500, 10537500, 38125000, 137937500, 499062500, 1805625000, 6532812500, 23635937500, 85515625000, 309398437500, 1119414062500, 4050078125000, 14653320312500

Offset: 1

Author

Joseph Myers, Dec 24 2008

Keywords

• nonn
• easy

Links

• Joseph Myers, BMO 2008--2009 Round 1 Problem 1---Generalisation

Crossrefs

Cf. A153362, A153363, A153364, A153366, A153367.

Formula

Empirical G.f.: x*(8-12*x)/(1-5*x+5*x^2). - Colin Barker, Jan 04 2012