# A128496 (b-file synthesized from sequence entry) 0 1 1 2 2 4 3 9 4 20 5 50 6 125 7 324 8 840 9 2195 10 5736 11 15012 12 39289 13 102854 14 269260 15 704925 16 1845500 17 4831574 18 12649205 19 33116040 20 86698896 21 226980647 22 594243024 23 1555748424 24 4073002225 25 10663258250 26 27916772500 27 73087059249 28 191344405220