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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 13 |
| 4 | 104 |
| 5 | 1111 |
| 6 | 14706 |
| 7 | 233017 |
| 8 | 4304672 |
| 9 | 90909091 |
| 10 | 2161452050 |
| 11 | 57154490053 |
| 12 | 1664148937320 |
| 13 | 52914318216943 |
| 14 | 1824557876586914 |
| 15 | 67818912035696881 |
| 16 | 2703399548648159360 |
| 17 | 115047976828352449051 |
| 18 | 5206367514895562076642 |
| 19 | 249660952380952380952381 |
[0,1,2,13,104,1111,14706,233017,4304672,90909091, 2161452050,57154490053,1664148937320, 52914318216943,1824557876586914,67818912035696881, 2703399548648159360,115047976828352449051, 5206367514895562076642,249660952380952380952381] |