448063domain: NAppears in sequencesa(n) = n*(n+1)^2*(n+2)^2/12.at n=21A004282a(n) = C(n,a)*C(n,b)*C(n,c)... where n = abc... are the decimal digits of n.at n=22A111695a(n) is the number of subsets of {1..n} that contain exactly 2 odd and 3 even numbers.at n=46A330300