553308domain: NAppears in sequencesa(n+1) = Sum_{k=0..sqrt(n)} a(k) * a(n-k).at n=19A030041Number of permutations satisfying -k<=p(i)-i<=r and p(i)-i not in I, i=1..n, with k=1, r=5, I={0,2}.at n=40A079966