# A243585 (b-file synthesized from sequence entry) 0 1 1 4 2 20 3 106 4 580 5 3244 6 18446 7 106250 8 618340 9 3628600 10 21438820 11 127377980 12 760346350 13 4556473276 14 27396081950 15 165189725326 16 998492094244 17 6048338850560 18 36706629690824 19 223139239595840 20 1358475322091620