# A005396 (b-file synthesized from sequence entry) 2 1 3 0 4 0 5 6 6 0 7 30 8 24 9 168 10 288 11 1170 12 2760 13 9504 14 25776 15 84006 16 244104 17 779970 18 2356800 19 7487310 20 23167656 21 73639326 22 231348000 23 737718534 24 2341772136 25 7498417956 26 23982456384 27 77119604400 28 248088123192 29 800978437674 30 2588744704560 31 8388692108016 32 27217694697000