# A024961 (b-file synthesized from sequence entry) 1 2 2 1 3 3 4 6 5 12 6 33 7 84 8 204 9 507 10 1410 11 3828 12 10185 13 27048 14 78720 15 222051 16 613770 17 1704360 18 4978050 19 14312460 20 40615440 21 115306545 22 341021994 23 994082808 24 2865120612 25 8271370236 26 24556630128 27 72215184450 28 210645965832 29 614238371328 30 1836536385786