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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 9 |
| 5 | 21 |
| 6 | 201 |
| 7 | 1191 |
| 8 | 4593 |
| 9 | 36009 |
| 10 | 620721 |
| 11 | 5297931 |
| 12 | 40360761 |
| 13 | 474989373 |
| 14 | 4345942329 |
| 15 | 122776895151 |
| 16 | 2118941145441 |
| 17 | 21344580276561 |
| 18 | 303071564084193 |
| 19 | 4476037678611219 |
| 20 | 59935820004483561 |
| 21 | 3838519441659950181 |
| 22 | 78361805638079449641 |
| 23 | 949279542954821272503 |
[1,1,1,3,9,21,201,1191,4593,36009,620721,5297931, 40360761,474989373,4345942329,122776895151, 2118941145441,21344580276561,303071564084193, 4476037678611219,59935820004483561, 3838519441659950181,78361805638079449641, 949279542954821272503] |