# A373277 (b-file synthesized from sequence entry) 1 1 2 3 3 16 4 84 5 480 6 2792 7 16807 8 102900 9 640528 10 4035120 11 25679568 12 164775800 13 1064714400 14 6920635197 15 45214871360 16 296722542900 17 1954878268800 18 12923917122536 19 85705978837392 20 569944757250960 21 3799631728452112 22 25388448354582216 23 169992219503608176