# A025558 (b-file synthesized from sequence entry) 1 1 2 4 3 9 4 48 5 50 6 360 7 735 8 2240 9 2268 10 25200 11 25410 12 332640 13 334620 14 336336 15 675675 16 11531520 17 11571560 18 220540320 19 221152932 20 221707200 21 222211080 22 5121436320 23 5131136010 24 25700298624 25 25741485000 26 77338861600 27 77445096300 28 2248776129600 29 2251453244040