# A006425 (b-file synthesized from sequence entry) 1 4 2 79 3 900 4 7885 5 59080 6 398846 7 2499096 8 14805705 9 83969600 10 459868530 11 2447439384 12 12718070274 13 64766697520 14 324156347260 15 1598200903280 16 7776728909121 17 37404399901296 18 178060831286890 19 839857764202520 20 3928581810398630 21 18239060530882224 22 84101317494787684