# A028214 (b-file synthesized from sequence entry) 0 1 1 36 2 820 3 15120 4 246736 5 3721536 6 53174080 7 730794240 8 9758653696 9 127501710336 10 1638112752640 11 20771546664960 12 260668843872256 13 3244288806567936 14 40111449573376000 15 493276560759521280 16 6039827824481468416 17 73691981266726158336 18 896516001844367196160