# A000535 (b-file synthesized from sequence entry) 1 0 2 27 3 378 4 4536 5 48600 6 489780 7 4738104 8 44535456 9 409752432 10 3708359550 11 33125746500 12 292779558720 13 2565087894720 14 22307854940280 15 192788833482000 16 1657111548654720 17 14176605442521312 18 120779466450505758 19 1025230099571720676 20 8674221270307971600