# A217664 (b-file synthesized from sequence entry) 0 1 1 1 2 2 3 7 4 23 5 72 6 227 7 725 8 2332 9 7537 10 24465 11 79720 12 260633 13 854539 14 2808768 15 9252315 16 30536925 17 100959558 18 334301159 19 1108483583 20 3680134756 21 12231824111 22 40697552035 23 135536687436 24 451776392011 25 1507088458381 26 5031254413136 27 16807872970501 28 56185887793379