187432domain: NAppears in sequencesa(n) = Sum_{k=0..[n/2]} 2^(n-2*k-1)*C(n-1,2*k)*C(2*k,k)/(k+1)*a(k), with a(0)=1.at n=11A118929Number of alternating sign matrices of size n which are indecomposable by direct and skew sums.at n=7A363689