# A158978 (b-file synthesized from sequence entry) 1 1 2 1 3 1 4 1 5 4 6 1 7 24 8 6 9 192 10 432 11 17280 12 10 13 207360 14 51840 15 322560 16 1360800 17 696729600 18 3225600 19 12541132800 20 39191040 21 27869184000 22 1316818944000 23 115880067072000 24 349272000 25 2781121609728000 26 17382010060800000