98547domain: NAppears in sequencesRectangular array of coefficients in successive iterations of x*exp(x), as read by antidiagonals.at n=42A174480a(n) = coefficient of x^n/(n-1)! in the 3-fold iteration of x*exp(x).at n=6A174493a(n) is the number of distinct billiard words with length n on an alphabet of 3 symbols.at n=16A180238