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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 31 |
| 2 | 495 |
| 3 | 5425 |
| 4 | 45879 |
| 5 | 319145 |
| 6 | 1900920 |
| 7 | 9965384 |
| 8 | 46909324 |
| 9 | 201295028 |
| 10 | 796809245 |
| 11 | 2937251395 |
| 12 | 10161553364 |
| 13 | 33205476524 |
| 14 | 103050077489 |
| 15 | 305131440111 |
| 16 | 865481871426 |
| 17 | 2359754902590 |
| 18 | 6203436293890 |
| 19 | 15765840836350 |
| 20 | 38828731002622 |
[1,31,495,5425,45879,319145,1900920,9965384, 46909324,201295028,796809245,2937251395, 10161553364,33205476524,103050077489,305131440111, 865481871426,2359754902590,6203436293890, 15765840836350,38828731002622] |