# A012075 (b-file synthesized from sequence entry) 0 1 1 1 2 1 3 4 4 13 5 76 6 421 7 3424 8 26713 9 285136 10 2871241 11 38302144 12 473357413 13 7603381696 14 111506036461 15 2097552753664 16 35624155784113 17 768471264000256 18 14838126699784081 19 361133162545705984