158580domain: NAppears in sequencesa(n) = Sum_{k=0..n} q(n,k) * !k, where q(n,k) = number of partitions of n into k distinct parts and !k = subfactorial of k.at n=38A331518Number of intersection points formed by drawing all least squares regression lines fitted to n points (j,y_j), 0 <= j < n, where each y_j is 0 or 1.at n=15A371437