| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 2 |
| 5 | 5 |
| 6 | 17 |
| 7 | 43 |
| 8 | 124 |
| 9 | 338 |
| 10 | 941 |
| 11 | 2591 |
| 12 | 7234 |
| 13 | 20125 |
| 14 | 56407 |
| 15 | 158349 |
| 16 | 446492 |
| 17 | 1262225 |
| 18 | 3580330 |
| 19 | 10181479 |
| 20 | 29031306 |
| 21 | 82968799 |
| 22 | 237642659 |
| 23 | 682014587 |
| 24 | 1960974220 |
| 25 | 5647919640 |
| 26 | 16292741605 |
| 27 | 47069104274 |
| 28 | 136166647110 |
| 29 | 394418199725 |
| 30 | 1143821887473 |
| 31 | 3320790074371 |
[0,0,1,2,5,17,43,124,338,941,2591,7234,20125, 56407,158349,446492,1262225,3580330,10181479, 29031306,82968799,237642659,682014587,1960974220, 5647919640,16292741605,47069104274,136166647110, 394418199725,1143821887473,3320790074371] |