# A148455 (b-file synthesized from sequence entry) 0 1 1 1 2 2 3 6 4 18 5 54 6 189 7 633 8 2304 9 8304 10 31165 11 117040 12 450812 13 1738597 14 6832754 15 26873783 16 107237479 17 428294527 18 1729570438 19 6992686966 20 28512482373 21 116421902463 22 478533610040 23 1969894917140 24 8152045246384 25 33786980247672 26 140634663815895 27 586246071077852 28 2452450863163104