405845domain: NAppears in sequencesa(n) = n*a(n-1) - a(n-2) + 1 + (-1)^n.at n=9A003470Numbers n such that n divides the (left) concatenation of all numbers <= n written in base 16 (most significant digit on right).at n=16A061969a(n) = Sum_{0<=m<n} Product_{-m<=j<=m} (n-j).at n=5A279127