# A113247 (b-file synthesized from sequence entry) 0 1 1 1 2 2 3 4 4 16 5 64 6 384 7 2544 8 20352 9 181632 10 1816320 11 19960320 12 239523840 13 3113533440 14 43589468160 15 653837506560 16 10461400104960 17 177843719208960 18 3201186945761280 19 60822550297313280 20 1216451005946265600