# A037634 (b-file synthesized from sequence entry) 1 2 2 13 3 81 4 488 5 2929 6 17577 7 105464 8 632785 9 3796713 10 22780280 11 136681681 12 820090089 13 4920540536 14 29523243217 15 177139459305 16 1062836755832 17 6377020534993 18 38262123209961 19 229572739259768 20 1377436435558609