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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 21 |
| 3 | 193 |
| 4 | 2669 |
| 5 | 48711 |
| 6 | 1113325 |
| 7 | 30615019 |
| 8 | 984983193 |
| 9 | 36319515355 |
| 10 | 1510538562641 |
| 11 | 69968975169567 |
| 12 | 3572684914283941 |
| 13 | 199389519518767111 |
| 14 | 12075888110164192917 |
| 15 | 788850329621989132771 |
| 16 | 55289606764547108653361 |
| 17 | 4138807268239824817387443 |
| 18 | 329564746571982961088975257 |
[1,4,21,193,2669,48711,1113325,30615019,984983193, 36319515355,1510538562641,69968975169567, 3572684914283941,199389519518767111, 12075888110164192917,788850329621989132771, 55289606764547108653361,4138807268239824817387443, 329564746571982961088975257] |