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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 16 |
| 5 | 74 |
| 6 | 427 |
| 7 | 2901 |
| 8 | 22625 |
| 9 | 199095 |
| 10 | 1951128 |
| 11 | 21072176 |
| 12 | 248651669 |
| 13 | 3182741352 |
| 14 | 43921830648 |
| 15 | 650043093589 |
| 16 | 10270680878694 |
| 17 | 172547438762056 |
| 18 | 3071344409964595 |
| 19 | 57741274907334371 |
| 20 | 1143277243165220534 |
[1,1,2,5,16,74,427,2901,22625,199095,1951128, 21072176,248651669,3182741352,43921830648, 650043093589,10270680878694,172547438762056, 3071344409964595,57741274907334371, 1143277243165220534] |