# A227791 (b-file synthesized from sequence entry) 0 1 1 2 2 8 3 36 4 176 5 940 6 5568 7 37128 8 280992 9 2410812 10 23250080 11 249164344 12 2934303264 13 37617633976 14 521009920256 15 7748175156240 16 123095897716800 17 2080205257723740 18 37253560076385120 19 704703668205036120 20 14039778681732928800 21 293831851498842784680