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A153372 Number of zig-zag paths from top to bottom of a rectangle of width 11 with 2n-1 rows whose color is that of the top right corner. 5
6, 20, 72, 264, 976, 3624, 13488, 50264, 187440, 699240, 2609008, 9735768, 36332016, 135588200, 506012592, 1888445784, 7047737776, 26302439784, 98161890288, 366344859224, 1367217022320, 5102522181480, 19042869606448 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..23.

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

FORMULA

Empirical g.f. -2*x*(3-8*x+3*x^2) / ( (2*x-1)*(x^2-4*x+1) ) with a(n)= +6*a(n-1) -9*a(n-2) +2*a(n-3) and a(n) = (2^n+8*A001075(n))/3. - R. J. Mathar, Jun 16 2011

CROSSREFS

A153368, A153369, A153370, A153371, A153373

Sequence in context: A146891 A235367 A189604 * A028402 A092760 A240043

Adjacent sequences:  A153369 A153370 A153371 * A153373 A153374 A153375

KEYWORD

easy,nonn

AUTHOR

Joseph Myers, Dec 24 2008

STATUS

approved

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Last modified May 21 15:27 EDT 2019. Contains 323444 sequences. (Running on oeis4.)