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| n | a(n) |
|---|---|
| 1 | 2 |
| 2 | 11 |
| 3 | 61 |
| 4 | 359 |
| 5 | 2153 |
| 6 | 12917 |
| 7 | 77491 |
| 8 | 464941 |
| 9 | 2789629 |
| 10 | 16737761 |
| 11 | 100426553 |
| 12 | 602559311 |
| 13 | 3615355859 |
| 14 | 21692135119 |
| 15 | 130152810703 |
| 16 | 780916864207 |
| 17 | 4685501185193 |
| 18 | 28113007111153 |
| 19 | 168678042666907 |
| 20 | 1012068256001351 |
| 21 | 6072409536008087 |
| 22 | 36434457216048503 |
| 23 | 218606743296291011 |
[2,11,61,359,2153,12917,77491,464941,2789629, 16737761,100426553,602559311,3615355859, 21692135119,130152810703,780916864207, 4685501185193,28113007111153,168678042666907, 1012068256001351,6072409536008087, 36434457216048503,218606743296291011] |