# A056268 (b-file synthesized from sequence entry) 1 0 2 0 3 6 4 36 5 150 6 534 7 1806 8 5760 9 18144 10 55830 11 171006 12 518580 13 1569750 14 4732014 15 14250450 16 42844320 17 128746950 18 386615376 19 1160688606 20 3483582660 21 10454059938 22 31368305694 23 94118013006 24 282378679920 25 847187946000 26 2541662931990 27 7625194813656 28 22875982414740