16904053domain: NAppears in sequencesExpansion of 1/((1-x) * (1-2*x) * (1-3*x) * (1-4*x))^2.at n=8A383842a(n) = [x^(2*n)] Product_{k=0..n} 1/(1 - k*x)^2.at n=4A384205