# A068578 (b-file synthesized from sequence entry) 1 2 2 3 3 4 4 6 5 8 6 10 7 12 8 14 9 16 10 18 11 20 12 24 13 30 14 36 15 40 16 42 17 48 18 60 19 72 20 84 21 90 22 120 23 180