A153370 Number of zig-zag paths from top to bottom of a rectangle of width 11 with n rows whose color is not that of the top right corner.

5, 10, 18, 36, 66, 132, 244, 488, 906, 1812, 3372, 6744, 12566, 25132, 46860, 93720, 174810, 349620, 652252, 1304504, 2433942, 4867884, 9083004, 18166008, 33897050, 67794100, 126503148, 253006296, 472111446, 944222892, 1761934444, 3523868888

Offset

1,1

Links

Table of n, a(n) for n=1..32.

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

Index entries for linear recurrences with constant coefficients, signature (0, 6, 0, -9, 0, 2).

Formula

Empirical: G.f. -x*(2*x+1)*(3*x^4-12*x^2+5) / ( (2*x^2-1)*(x^4-4*x^2+1) ) and a(n)= +6*a(n-2) -9*a(n-4) +2*a(n-6). - R. J. Mathar, Jun 16 2011

Crossrefs

A153368, A153369, A153372. Bisections: A153371, A153373.

Sequence in context: A226445 A296552 A251928 * A119135 A083287 A091922

Adjacent sequences: A153367 A153368 A153369 * A153371 A153372 A153373

Keyword

easy,nonn

Author

Joseph Myers, Dec 24 2008

Status

approved