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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 18 |
| 5 | 62 |
| 6 | 216 |
| 7 | 787 |
| 8 | 2977 |
| 9 | 11605 |
| 10 | 46467 |
| 11 | 190494 |
| 12 | 797508 |
| 13 | 3402436 |
| 14 | 14766894 |
| 15 | 65102146 |
| 16 | 291182808 |
| 17 | 1319875827 |
| 18 | 6057465890 |
| 19 | 28124389866 |
| 20 | 132006302556 |
| 21 | 625958670808 |
| 22 | 2996991862997 |
| 23 | 14480681454264 |
| 24 | 70575215105489 |
[1,2,6,18,62,216,787,2977,11605,46467,190494, 797508,3402436,14766894,65102146,291182808, 1319875827,6057465890,28124389866,132006302556, 625958670808,2996991862997,14480681454264, 70575215105489] |