# A073964 (b-file synthesized from sequence entry) 1 0 2 2 3 6 4 20 5 100 6 600 7 3150 8 15750 9 78000 10 390000 11 1952500 12 9768750 13 48831250 14 244125000 15 1220625000 16 6103437500 17 30517656250 18 152588281250 19 762939062500 20 3814695312500 21 19073484375000 22 95367441406250 23 476837167968750 24 2384185742187500 25 11920928710937500