25027296domain: NAppears in sequencesWhitney number of level n of the lattice of the ideals of the fence of order 2n.at n=20A051286Largest Whitney number of Fibonacci lattices J(Z_n).at n=40A077419Binomial sums a(n) = Sum_{k=0..n} (binomial(2n-k,k))^2.at n=10A188648