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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 13 |
| 4 | 50 |
| 5 | 205 |
| 6 | 865 |
| 7 | 3740 |
| 8 | 16580 |
| 9 | 74723 |
| 10 | 340133 |
| 11 | 1566675 |
| 12 | 7278445 |
| 13 | 34032294 |
| 14 | 160099893 |
| 15 | 757146959 |
| 16 | 3595868383 |
| 17 | 17142001362 |
| 18 | 81998483431 |
| 19 | 393381923307 |
| 20 | 1892091356534 |
| 21 | 9122041253349 |
| 22 | 44070811591388 |
| 23 | 213315103504276 |
| 24 | 1034271774573223 |
| 25 | 5022540629529213 |
| 26 | 24424433945271885 |
| 27 | 118928982595806325 |
[1,1,4,13,50,205,865,3740,16580,74723,340133, 1566675,7278445,34032294,160099893,757146959, 3595868383,17142001362,81998483431,393381923307, 1892091356534,9122041253349,44070811591388, 213315103504276,1034271774573223,5022540629529213, 24424433945271885,118928982595806325] |