# A012150 (b-file synthesized from sequence entry) 0 1 1 1 2 1 3 4 4 13 5 76 6 421 7 3256 8 25369 9 245008 10 2449801 11 28441216 12 346065061 13 4700478784 14 67243537453 15 1047088053376 16 17192488230961 17 302112622479616 18 5593309059948049 19 109527844826856448 20 2255588021494237501