# A103334 (b-file synthesized from sequence entry) 0 1 1 1 2 4 3 24 4 176 5 1376 6 10944 7 87424 8 699136 9 5592576 10 44739584 11 357914624 12 2863312896 13 22906494976 14 183251943424 15 1466015514624 16 11728124051456 17 93824992280576 18 750599937982464 19 6004799503335424 20 48038396025634816