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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 18 |
| 2 | 144 |
| 3 | 702 |
| 4 | 2448 |
| 5 | 6786 |
| 6 | 15984 |
| 7 | 33390 |
| 8 | 63648 |
| 9 | 112914 |
| 10 | 189072 |
| 11 | 301950 |
| 12 | 463536 |
| 13 | 688194 |
| 14 | 992880 |
| 15 | 1397358 |
| 16 | 1924416 |
| 17 | 2600082 |
| 18 | 3453840 |
| 19 | 4518846 |
| 20 | 5832144 |
| 21 | 7434882 |
| 22 | 9372528 |
| 23 | 11695086 |
| 24 | 14457312 |
| 25 | 17718930 |
| 26 | 21544848 |
| 27 | 26005374 |
| 28 | 31176432 |
| 29 | 37139778 |
| 30 | 43983216 |
[1,18,144,702,2448,6786,15984,33390,63648,112914, 189072,301950,463536,688194,992880,1397358, 1924416,2600082,3453840,4518846,5832144,7434882, 9372528,11695086,14457312,17718930,21544848, 26005374,31176432,37139778,43983216] |