# A163640 (b-file synthesized from sequence entry) 0 1 1 6 2 30 3 70 4 210 5 462 6 6006 7 4290 8 72930 9 461890 10 1939938 11 4056234 12 6760390 13 1560090 14 6463230 15 200360130 16 2203961430 17 907513530 18 33578000610 19 22974421470 20 941951280270