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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 13 |
| 4 | 49 |
| 5 | 241 |
| 6 | 2401 |
| 7 | 13021 |
| 8 | 128353 |
| 9 | 1346689 |
| 10 | 10615681 |
| 11 | 140431501 |
| 12 | 1544877841 |
| 13 | 17576665393 |
| 14 | 264566466529 |
| 15 | 3226728670621 |
| 16 | 48376006929601 |
| 17 | 766753039205761 |
| 18 | 11052669865900033 |
| 19 | 197019825098096269 |
| 20 | 3271213100827557361 |
| 21 | 56597110823949654001 |
[1,1,1,13,49,241,2401,13021,128353,1346689, 10615681,140431501,1544877841,17576665393, 264566466529,3226728670621,48376006929601, 766753039205761,11052669865900033, 197019825098096269,3271213100827557361, 56597110823949654001] |