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Search: id:A153334
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| A153334 |
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Number of zig-zag paths from top to bottom of an n by n square whose color is that of the top right corner |
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+0
5
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| 1, 1, 4, 8, 24, 52, 136, 296, 720, 1556, 3624, 7768, 17584, 37416, 83024, 175568, 383904, 807604, 1746280, 3657464, 7839216, 16357496, 34812144, 72407728, 153204064, 317777032, 669108496, 1384524656, 2903267040, 5994736336
(list; graph; listen)
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OFFSET
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1,3
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LINKS
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Joseph Myers, BMO 2008--2009 Round 1 Problem 1---Generalisation
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FORMULA
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a(n) = (n+1)2^(n-2) - 2(n-1)binomial(n-2,(n-2)/2) for n even, a(n) = (n+1)2^(n-2) - (n-1)binomial(n-1,(n-1)/2) for n odd
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CROSSREFS
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A102699, A153335, A153336, A153337, A153338
Sequence in context: A062015 A006640 A115641 this_sequence A159612 A099176 A116556
Adjacent sequences: A153331 A153332 A153333 this_sequence A153335 A153336 A153337
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KEYWORD
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easy,nonn
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AUTHOR
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Joseph Myers (jsm(AT)polyomino.org.uk), Dec 24 2008
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