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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. 4
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

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

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

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Last modified January 24 19:19 EST 2020. Contains 331211 sequences. (Running on oeis4.)