1,1

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

(PARI) a(n)=(1/3-1/12*binomial(2*n, n)^3/binomial(6*n, 3*n))*prod(i=1, 2*n, prod(j=1, 2*n, prod(k=1, 2*n, (i+j+k-1)/(i+j+k-2))))

Cf. A099112-A099117, A008793.

Adjacent sequences: A099109 A099110 A099111 this_sequence A099113 A099114 A099115

Sequence in context: A076913 A101450 A101439 this_sequence A086897 A034208 A003834

nonn

Ralf Stephan, Oct 01 2004