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A099115
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Number of rhombus tilings of a hexagon with side lengths 2n+1,2n-1,2n+1,2n+1,2n-1,2n+1 which contain the rhombus above and next to the center of the hexagon.
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0
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OFFSET
| 1,1
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LINKS
| M. Fulmek and C. Krattenthaler, [math/9909038] The number of rhombus tilings of a symmetric hexagon which contain a fixed rhombus on the symmetry axis, II
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PROG
| (PARI) a(n)=(1/3+(10*n+3)/(24*n)*binomial(2*n, n)^3/binomial(6*n, 3*n))*prod(i=1, 2*n+1, prod(j=1, 2*n-1, prod(k=1, 2*n+1, (i+j+k-1)/(i+j+k-2))))
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CROSSREFS
| Cf. A099112-A099117, A008793.
Sequence in context: A098880 A076173 A100108 * A076171 A090102 A112854
Adjacent sequences: A099112 A099113 A099114 * A099116 A099117 A099118
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KEYWORD
| nonn
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AUTHOR
| Ralf Stephan, Oct 01 2004
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