# A004352 (b-file synthesized from sequence entry) 10 1 11 55 12 1770 13 43680 14 916895 15 17259390 16 300500200 17 4935847320 18 77515521435 19 1174992339235 20 17310309456440 21 249145778809200 22 3517322746798575 23 48857840214014580 24 669413654240461560 25 9064807833193439800