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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 38 |
| 5 | 302 |
| 6 | 3428 |
| 7 | 55083 |
| 8 | 1251590 |
| 9 | 40289986 |
| 10 | 1841412556 |
| 11 | 119672298150 |
| 12 | 11071253179356 |
| 13 | 1459246211179612 |
| 14 | 274215745471606536 |
| 15 | 73511068056751643571 |
| 16 | 28128768433558172885958 |
| 17 | 15371204139970896651788090 |
| 18 | 12001328910786418412379456956 |
[1,1,2,7,38,302,3428,55083,1251590,40289986, 1841412556,119672298150,11071253179356, 1459246211179612,274215745471606536, 73511068056751643571,28128768433558172885958, 15371204139970896651788090, 12001328910786418412379456956] |