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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 13 |
| 3 | 124 |
| 4 | 1427 |
| 5 | 18424 |
| 6 | 257090 |
| 7 | 3794091 |
| 8 | 58411957 |
| 9 | 929535968 |
| 10 | 15190791558 |
| 11 | 253735278108 |
| 12 | 4316305707838 |
| 13 | 74571507312612 |
| 14 | 1305616160300541 |
| 15 | 23124883139330156 |
| 16 | 413757060245969804 |
| 17 | 7469673227755295934 |
| 18 | 135931742489359394834 |
| 19 | 2491396081566293784574 |
| 20 | 45957915237430642944461 |
[1,2,13,124,1427,18424,257090,3794091,58411957, 929535968,15190791558,253735278108,4316305707838, 74571507312612,1305616160300541,23124883139330156, 413757060245969804,7469673227755295934, 135931742489359394834,2491396081566293784574, 45957915237430642944461] |