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| n | a(n) |
|---|---|
| 1 | 20 |
| 2 | 400 |
| 3 | 3860 |
| 4 | 32204 |
| 5 | 262588 |
| 6 | 2065977 |
| 7 | 16000078 |
| 8 | 122025944 |
| 9 | 922211892 |
| 10 | 6920848521 |
| 11 | 51700037261 |
| 12 | 384921049976 |
| 13 | 2859343329045 |
| 14 | 21205878606102 |
| 15 | 157093241661662 |
| 16 | 1162816498531534 |
| 17 | 8602424081844841 |
| 18 | 63614642982706249 |
[20,400,3860,32204,262588,2065977,16000078, 122025944,922211892,6920848521,51700037261, 384921049976,2859343329045,21205878606102, 157093241661662,1162816498531534,8602424081844841, 63614642982706249] |