# A121517 (b-file synthesized from sequence entry) 0 1 1 1 2 7 3 31 4 151 5 721 6 3457 7 16561 8 79351 9 380191 10 1821607 11 8727841 12 41817601 13 200360161 14 959983207 15 4599555871 16 22037796151 17 105589424881 18 505909328257 19 2423957216401 20 11613876753751 21 55645426552351 22 266613256008007