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, 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

Links

Table of n, a(n) for n=1..24.

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

Crossrefs

A153362, A153363, A153364, A153365, A153367

Sequence in context: A268225 A120343 A301280 * A057553 A226973 A006217

Adjacent sequences: A153363 A153364 A153365 * A153367 A153368 A153369

Keyword

nonn,easy

Author

Joseph Myers, Dec 24 2008

Status

approved