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A340352
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Number of spanning trees of odd Aztec diamond OD_n.
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2
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1, 192, 4542720, 12116689944576, 3544863978266468352000, 112387469554685044937510092800000, 383669915612621265759587438135691539652804608, 140496256399491641572818822014023027580848616806252629983232
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OFFSET
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1,2
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COMMENTS
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R. P. Stanley conjectured that the even Aztec diamond has exactly four times as many spanning trees as the odd Aztec diamond. This conjecture was first proved by D. E. Knuth.
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OD_1 OD_2 OD_3
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LINKS
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FORMULA
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a(n) = 4^(2*(n-1)) * A340166(n) = 4^(2*(n-1)*n) * Product_{1<=j,k<=n-1} (1 - sin(j*Pi/(2*n))^2 * sin(k*Pi/(2*n))^2).
a(n) ~ Gamma(1/4) * exp(8*G*n^2/Pi) / (Pi^(3/4) * sqrt(n) * 2^(2*n + 2)), where G is Catalan's constant A006752. - Vaclav Kotesovec, Jan 06 2021
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PROG
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(PARI) default(realprecision, 120);
{a(n) = round(4^(2*(n-1)*n)*prod(j=1, n-1, prod(k=1, n-1, 1-(sin(j*Pi/(2*n))*sin(k*Pi/(2*n)))^2)))}
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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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