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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 257 |
| 3 | 6818 |
| 4 | 105250 |
| 5 | 2175491 |
| 6 | 44988020 |
| 7 | 796565173 |
| 8 | 13803604854 |
| 9 | 240522266760 |
| 10 | 4044067171130 |
| 11 | 65769795259820 |
| 12 | 1051279656603367 |
| 13 | 16517653032316394 |
| 14 | 254354069377336990 |
| 15 | 3847172021760617755 |
| 16 | 57300325471166205776 |
| 17 | 840900188345961238222 |
| 18 | 12164188625099191500782 |
[1,1,257,6818,105250,2175491,44988020,796565173, 13803604854,240522266760,4044067171130, 65769795259820,1051279656603367,16517653032316394, 254354069377336990,3847172021760617755, 57300325471166205776,840900188345961238222, 12164188625099191500782] |