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| n | a(n) |
|---|---|
| 1 | 20 |
| 2 | 400 |
| 3 | 6796 |
| 4 | 112436 |
| 5 | 1859020 |
| 6 | 30756756 |
| 7 | 508916456 |
| 8 | 8420768936 |
| 9 | 139333478144 |
| 10 | 2305467501680 |
| 11 | 38147189410288 |
| 12 | 631198698504112 |
| 13 | 10444066884547776 |
| 14 | 172811720487440320 |
| 15 | 2859412053301829248 |
| 16 | 47312978931444876928 |
[20,400,6796,112436,1859020,30756756,508916456, 8420768936,139333478144,2305467501680, 38147189410288,631198698504112,10444066884547776, 172811720487440320,2859412053301829248, 47312978931444876928] |