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+1/3*binomial(2*n, n)^3/binomial(6*n+2, 3*n+1))*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))))

Cf. A099112-A099117, A008793.

Sequence in context: A140935 A022196 A098252 this_sequence A073304 A011763 A116354

Adjacent sequences: A099110 A099111 A099112 this_sequence A099114 A099115 A099116

nonn

Ralf Stephan, Oct 01 2004