# A187980 (b-file synthesized from sequence entry) 1 0 2 1 3 3 4 9 5 36 6 117 7 411 8 1452 9 5040 10 17829 11 62870 12 222458 13 789895 14 2808018 15 10006020 16 35713288 17 127657287 18 456975112 19 1637845137 20 5876993799 21 21110257429 22 75900966585 23 273140226328 24 983733709424 25 3545658087397 26 12788512426396 27 46155740640489 28 166684398100813 29 602296651467057 30 2177492178467267 31 7876245417001355