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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 684 |
| 2 | 62054 |
| 3 | 1759704 |
| 4 | 21210156 |
| 5 | 140116184 |
| 6 | 658369608 |
| 7 | 2449182384 |
| 8 | 7597766246 |
| 9 | 20748447108 |
| 10 | 50601708504 |
| 11 | 114223115480 |
| 12 | 238352317656 |
| 13 | 472600643976 |
| 14 | 883678139136 |
| 15 | 1594639240368 |
| 16 | 2749536787500 |
| 17 | 4620722631088 |
| 18 | 7482364853310 |
| 19 | 11894205734280 |
| 20 | 18321074279384 |
[1,684,62054,1759704,21210156,140116184,658369608, 2449182384,7597766246,20748447108,50601708504, 114223115480,238352317656,472600643976, 883678139136,1594639240368,2749536787500, 4620722631088,7482364853310,11894205734280, 18321074279384] |