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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 62 |
| 3 | 290 |
| 4 | 1284 |
| 5 | 5902 |
| 6 | 27086 |
| 7 | 124436 |
| 8 | 572080 |
| 9 | 2629946 |
| 10 | 12090710 |
| 11 | 55591878 |
| 12 | 255589946 |
| 13 | 1175154022 |
| 14 | 5403111082 |
| 15 | 24842308392 |
| 16 | 114220099740 |
| 17 | 525160514282 |
| 18 | 2414582116408 |
| 19 | 11101765510580 |
| 20 | 51043677955498 |
| 21 | 234688597761528 |
[4,62,290,1284,5902,27086,124436,572080,2629946, 12090710,55591878,255589946,1175154022,5403111082, 24842308392,114220099740,525160514282, 2414582116408,11101765510580,51043677955498, 234688597761528] |