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A153369 Number of zig-zag paths from top to bottom of a rectangle of width 11 with n rows whose color is that of the top right corner. 4
6, 10, 20, 36, 72, 132, 264, 488, 976, 1812, 3624, 6744, 13488, 25132, 50264, 93720, 187440, 349620, 699240, 1304504, 2609008, 4867884, 9735768, 18166008, 36332016, 67794100, 135588200, 253006296, 506012592, 944222892, 1888445784, 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

Empirically, g.f. -2*x*(3+5*x-8*x^2-12*x^3+3*x^4+3*x^5) / ( (2*x^2-1)*(x^4-4*x^2+1) ) with a(n)= +6*a(n-2) -9*a(n-4) +2*a(n-6). - R. J. Mathar, Jun 16 2011

CROSSREFS

A153368, A153370, A153371, A153372, A153373

Sequence in context: A163172 A117348 A117349 * A107981 A065758 A254028

Adjacent sequences:  A153366 A153367 A153368 * A153370 A153371 A153372

KEYWORD

easy,nonn

AUTHOR

Joseph Myers, Dec 24 2008

STATUS

approved

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Last modified January 20 14:02 EST 2020. Contains 331094 sequences. (Running on oeis4.)