# A005305 (b-file synthesized from sequence entry) 2 2 3 4 4 8 5 16 6 30 7 56 8 100 9 172 10 290 11 480 12 780 13 1248 14 1970 15 3068 16 4724 17 7200 18 10862 19 16240 20 24080