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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 11 |
| 4 | 46 |
| 5 | 168 |
| 6 | 731 |
| 7 | 2979 |
| 8 | 13401 |
| 9 | 57661 |
| 10 | 265461 |
| 11 | 1181726 |
| 12 | 5522830 |
| 13 | 25155711 |
| 14 | 118893172 |
| 15 | 550284353 |
| 16 | 2622755672 |
| 17 | 12286768851 |
| 18 | 58931031929 |
| 19 | 278651004826 |
| 20 | 1343265798651 |
| 21 | 6397648075135 |
| 22 | 30966476881123 |
| 23 | 148352084091735 |
| 24 | 720436718946511 |
| 25 | 3467981145821313 |
| 26 | 16888078807378942 |
| 27 | 81615427515075795 |
[1,1,4,11,46,168,731,2979,13401,57661,265461, 1181726,5522830,25155711,118893172,550284353, 2622755672,12286768851,58931031929,278651004826, 1343265798651,6397648075135,30966476881123, 148352084091735,720436718946511,3467981145821313, 16888078807378942,81615427515075795] |