# A009458 (b-file synthesized from sequence entry) 0 0 1 0 2 2 3 -6 4 18 5 -60 6 214 7 -714 8 984 9 23040 10 -468880 11 7113040 12 -102747560 13 1501609200 14 -22698373400 15 358125772200 16 -5919450952000 17 102619545932800 18 -1865622384074400 19 35539903321740000 20 -708618759088892000 21 14768814409403208000