# A221704 (b-file synthesized from sequence entry) 2 20 3 96 4 440 5 1956 6 8522 7 36616 8 155748 9 657468 10 2759040 11 11523584 12 47944480 13 198834824 14 822365998 15 3393330152 16 13973673788 17 57441828332 18 235759507928 19 966292212992 20 3955570350128 21 16174269135992 22 66069496614548 23 269635886185424 24 1099484607270920 25 4479870682221016 26 18240349141736352 27 74219083904054016 28 301810005706454016