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A099114 Number of rhombus tilings of a hexagon with side lengths 2n,2n+2,2n,2n,2n+2,2n which contain the rhombus above and next to the center of the hexagon. 5
19, 2252052, 125575149020464, 3624877924928635307525440, 55204136490632334691332479792745796875, 446207680704793917097310140821019734826847707500000000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..6.

M. Fulmek and C. Krattenthaler, The number of rhombus tilings of a symmetric hexagon which contain a fixed rhombus on the symmetry axis, II, arXiv:math/9909038 [math.CO], 1999.

MATHEMATICA

G = BarnesG; a[n_] := (G[2n+1]^(2-2n) G[2n+3]^(1-2n)(G[2n+2] G[2n+4])^(2n) G[6n+3](1/3 - ((10n+2) Binomial[2n, n]^3)/((6n+3) Binomial[6n+2, 3n+1]))) /((G[4n+1] G[4n+3]^2) (Gamma[2n+1] Gamma[2n+3])^(2n)); Array[a, 6] (* Jean-François Alcover, Feb 20 2019 *)

PROG

(PARI) a(n)=(1/3-(10*n+2)/(6*n+3)*binomial(2*n, n)^3/binomial(6*n+2, 3*n+1))*prod(i=1, 2*n, prod(j=1, 2*n+2, prod(k=1, 2*n, (i+j+k-1)/(i+j+k-2))))

CROSSREFS

Cf. A099112, A099113, A099115, A099116, A099117, A008793.

Sequence in context: A172824 A070632 A234039 * A013810 A172875 A172839

Adjacent sequences: A099111 A099112 A099113 * A099115 A099116 A099117

KEYWORD

nonn

AUTHOR

Ralf Stephan, Oct 01 2004

STATUS

approved

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Last modified November 28 05:56 EST 2022. Contains 358407 sequences. (Running on oeis4.)