# A294513 (b-file synthesized from sequence entry) 0 2 1 5 2 120 3 1320 4 9240 5 52360 6 52360 7 602140 8 70450380 9 2043061020 10 16344488160 11 3268897632 12 62109055008 13 2546471255328 14 1157486934240 15 54401885909280 16 272009429546400 17 4805499921986400 18 4805499921986400 19 283524495397197600 20 418536159872053600