# A018676 (b-file synthesized from sequence entry) 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 10 10 12 11 14 12 15 13 20 14 21 15 24 16 28 17 30 18 35 19 40 20 42 21 56 22 60 23 70 24 84 25 105 26 120 27 140 28 168 29 210 30 280 31 420 32 840