# A124500 (b-file synthesized from sequence entry) 0 1 1 1 2 2 3 4 4 10 5 25 6 67 7 180 8 495 9 1375 10 3871 11 10993 12 31493 13 90843 14 263686 15 769466 16 2256135 17 6643082 18 19634705 19 58232350 20 173242381 21 516860717 22 1546035258 23 4635543843 24 13929569399 25 41943013047 26 126532961332 27 382396277940