# A147688 (b-file synthesized from sequence entry) 0 1 1 6 2 44 3 360 4 3088 5 26976 6 237248 7 2091648 8 18456832 9 162915840 10 1438198784 11 12696741888 12 112091336704 13 989587267584 14 8736489783296 15 77129433907200 16 680931492954112 17 6011553766047744 18 53072563389857792 19 468547255228956672