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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 12 |
| 4 | 38 |
| 5 | 143 |
| 6 | 527 |
| 7 | 1977 |
| 8 | 7851 |
| 9 | 31110 |
| 10 | 125198 |
| 11 | 515302 |
| 12 | 2125456 |
| 13 | 8872634 |
| 14 | 37425969 |
| 15 | 158422833 |
| 16 | 676318450 |
| 17 | 2903753155 |
| 18 | 12514755832 |
| 19 | 54252313270 |
| 20 | 236067482292 |
| 21 | 1030845976142 |
| 22 | 4519733509516 |
| 23 | 19873168554659 |
| 24 | 87648421496810 |
| 25 | 387702292340412 |
| 26 | 1719006136669141 |
| 27 | 7640989054526988 |
[1,1,4,12,38,143,527,1977,7851,31110,125198, 515302,2125456,8872634,37425969,158422833, 676318450,2903753155,12514755832,54252313270, 236067482292,1030845976142,4519733509516, 19873168554659,87648421496810,387702292340412, 1719006136669141,7640989054526988] |