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A242638
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Number of quadrangulations of a hexagon b_1 w_3 b_2 w_1 b_3 w_2 having n inner faces and not containing the edge b_1 w_1.
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2
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0, 0, 2, 10, 47, 226, 1122, 5738, 30107, 161460, 882180, 4897752, 27570532, 157083944, 904523386, 5257488138, 30814928707, 181966070440, 1081790956890, 6470568865530, 38917734372615, 235260687007290, 1428777440333880, 8714285083290072, 53359037547384852
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OFFSET
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0,3
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LINKS
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FORMULA
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G.f.: (2 - 6*g(x) + 3*g(x)^2)*g(x)^2/(1 - g(x))^4 where g(x)/x is the g.f. of A006013. - Andrew Howroyd, Feb 23 2020
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PROG
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(PARI) seq(n)={my(g=serreverse(x*(1-x)^2 + O(x^n))); Vec((2 - 6*g + 3*g^2)*g^2/(1 - g)^4, -(n+1))} \\ Andrew Howroyd, Feb 23 2020
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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