# A355994 (b-file synthesized from sequence entry) 0 0 1 0 2 0 3 3 4 6 5 20 6 270 7 1764 8 12600 9 169560 10 1937880 11 22300740 12 349806600 13 5556245760 14 89073856872 15 1678920566400 16 33550354656000 17 687175528253760 18 15462823882213440 19 370285712520237360 20 9180722384533375200 21 242398467521271149760