# A052824 (b-file synthesized from sequence entry) 0 0 1 0 2 2 3 6 4 34 5 220 6 1808 7 17388 8 194724 9 2478096 10 35418192 11 561533280 12 9785418432 13 185921027136 14 3825633439392 15 84756646285920 16 2011657535668128 17 50924796197369088 18 1369659967551038976 19 39003791158314816768 20 1172394903935534452992 21 37094744191300029964800