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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 9 |
| 3 | 36 |
| 4 | 84 |
| 5 | 126 |
| 6 | 126 |
| 7 | 84 |
| 8 | 36 |
| 9 | 9 |
| 10 | 1 |
| 11 | 81 |
| 12 | 2916 |
| 13 | 61236 |
| 14 | 826686 |
| 15 | 7440174 |
| 16 | 44641044 |
| 17 | 172186884 |
| 18 | 387420489 |
| 19 | 387420489 |
| 20 | 13947137604 |
| 21 | 223154201664 |
| 22 | 2082772548864 |
| 23 | 12496635293184 |
| 24 | 49986541172736 |
| 25 | 133297443127296 |
| 26 | 228509902503936 |
| 27 | 228509902503936 |
| 28 | 101559956668416 |
[1,1,9,36,84,126,126,84,36,9,1,81,2916,61236, 826686,7440174,44641044,172186884,387420489, 387420489,13947137604,223154201664,2082772548864, 12496635293184,49986541172736,133297443127296, 228509902503936,228509902503936,101559956668416] |