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1, 7, 78, 969, 12650, 169911, 2324784, 32224114, 450978066, 6358402050, 90177170226, 1285063345176, 18385569737808, 263926640438545, 3799541229226200, 54834293825867556, 793067310934426018
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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0,2
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COMMENTS
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a(n) is the number of paths from (0,0) to (6n,n) taking north and east steps and avoiding north^{=2}. - Shanzhen Gao, Apr 15 2010
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LINKS
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FORMULA
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a(n) is asymptotic to c*sqrt(n)*(46656/3125)^n with c= 0.5243... [c = 2*3^(3/2)/(5^(3/2)*sqrt(Pi)) = 0.52442324668419795386... - Vaclav Kotesovec, Feb 14 2019]
G.f.: hypergeom([1/3, 1/2, 2/3, 5/6, 7/6], [2/5, 3/5, 4/5, 6/5], (46656/3125)*x). - Robert Israel, Aug 07 2014
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MAPLE
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seq(binomial(6*n+1, n), n = 1 .. 100); # Robert Israel, Aug 07 2014
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MATHEMATICA
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PROG
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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