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| n | a(n) |
|---|---|
| 1 | 12 |
| 2 | 52 |
| 3 | 236 |
| 4 | 1076 |
| 5 | 4908 |
| 6 | 22388 |
| 7 | 102124 |
| 8 | 465844 |
| 9 | 2124972 |
| 10 | 9693172 |
| 11 | 44215916 |
| 12 | 201693236 |
| 13 | 920034348 |
| 14 | 4196785268 |
| 15 | 19143857644 |
| 16 | 87325717684 |
| 17 | 398340873132 |
| 18 | 1817052930292 |
| 19 | 8288582905196 |
| 20 | 37808808665396 |
| 21 | 172466877516588 |
[12,52,236,1076,4908,22388,102124,465844,2124972, 9693172,44215916,201693236,920034348,4196785268, 19143857644,87325717684,398340873132, 1817052930292,8288582905196,37808808665396, 172466877516588] |