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A026861
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T(2n,n+1), T given by A026747.
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0
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1, 5, 22, 95, 411, 1790, 7855, 34725, 154573, 692450, 3120206, 14135555, 64356345, 294341325, 1351889910, 6233399525, 28845511125, 133933280000, 623811120960, 2913924782375, 13648296620445, 64087737455725, 301644762913977
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OFFSET
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1,2
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COMMENTS
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a(n+1) = p(n+1) where p(x) is the unique degree-n polynomial such that p(k) = A002212(k+1) for k=0,1,...,n. - Michael Somos, Oct 07 2003
Number of skew Dyck paths of semilength n+1 containing at least one left step. - David Scambler, Jun 17 2013
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LINKS
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FORMULA
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PROG
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(PARI) a(n)=if(n<1, 0, subst(polinterpolate(Vec((1-3*x-sqrt(1-6*x+5*x^2+x^2*O(x^n)))/2)), x, n+1))
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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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