# A055891 (b-file synthesized from sequence entry) 0 1 1 2 2 7 3 20 4 64 5 200 6 686 7 2324 8 8194 9 29084 10 104860 11 381116 12 1398148 13 5161592 14 19173958 15 71580752 16 268435474 17 1010572832 18 3817749138 19 14467230668 20 54975581488 21 209430687944 22 799644820114 23 3059510251700 24 11728124035248