# A099177 (b-file synthesized from sequence entry) 0 0 1 1 2 2 3 8 4 20 5 60 6 160 7 448 8 1216 9 3344 10 9120 11 24960 12 68160 13 186304 14 508928 15 1390592 16 3799040 17 10379520 18 28357120 19 77473792 20 211661824 21 578272256 22 1579868160 23 4316282880 24 11792302080 25 32217174016 26 88018952192 27 240472260608