# A005947 (b-file synthesized from sequence entry) 0 0 1 3 2 16 3 75 4 356 5 1770 6 9306 7 51821 8 305232 9 1897227 10 12411650 11 85234864 12 612903324 13 4604004691 14 36050248752 15 293659886235 16 2483993559376 17 21781908622738 18 197701336871190 19 1854695911048053 20 17960309481562600 21 179309794875495795