# A047048 (b-file synthesized from sequence entry) 0 1 1 4 2 14 3 48 4 165 5 586 6 2114 7 7694 8 28173 9 104370 10 389751 11 1463288 12 5514820 13 20894454 14 79510118 15 303570094 16 1161991698 17 4460728710 18 17168879077 19 66225380848 20 255907081225 21 990671100502 22 3841609763148 23 14919279265464