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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 16 |
| 2 | 68 |
| 3 | 256 |
| 4 | 777 |
| 5 | 2160 |
| 6 | 5460 |
| 7 | 13056 |
| 8 | 29482 |
| 9 | 63952 |
| 10 | 133456 |
| 11 | 270080 |
| 12 | 531091 |
| 13 | 1019424 |
| 14 | 1913156 |
| 15 | 3520512 |
| 16 | 6360765 |
| 17 | 11305488 |
| 18 | 19789160 |
| 19 | 34159616 |
| 20 | 58201535 |
[1,16,68,256,777,2160,5460,13056,29482,63952, 133456,270080,531091,1019424,1913156,3520512, 6360765,11305488,19789160,34159616,58201535] |