| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 10 |
| 4 | 80 |
| 5 | 661 |
| 6 | 5802 |
| 7 | 54725 |
| 8 | 558704 |
| 9 | 6178565 |
| 10 | 73840164 |
| 11 | 950331113 |
| 12 | 13121175977 |
| 13 | 193618002604 |
| 14 | 3042570732326 |
| 15 | 50747501675076 |
| 16 | 895651186352884 |
| 17 | 16679929313440954 |
| 18 | 326936145826028780 |
| 19 | 6728526339596831313 |
| 20 | 145085354333183129464 |
| 21 | 3271200076443827203823 |
[1,1,2,10,80,661,5802,54725,558704,6178565, 73840164,950331113,13121175977,193618002604, 3042570732326,50747501675076,895651186352884, 16679929313440954,326936145826028780, 6728526339596831313,145085354333183129464, 3271200076443827203823] |