# A173927 (b-file synthesized from sequence entry) 1 1 2 2 3 3 4 5 5 11 6 23 7 47 8 283 9 719 10 1439 11 2879 12 34549 13 138197 14 531441 15 1594323 16 4782969 17 14348907 18 43046721 19 86093443 20 258280327 21 688747547