# A057513 (b-file synthesized from sequence entry) 0 1 1 1 2 2 3 4 4 9 5 21 6 56 7 153 8 451 9 1357 10 4212 11 13308 12 42898 13 140276 14 465324 15 1561955 16 5300285 17 18156813 18 62732842 19 218405402 20 765657940