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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 9 |
| 2 | 51 |
| 3 | 249 |
| 4 | 1387 |
| 5 | 7879 |
| 6 | 45663 |
| 7 | 267367 |
| 8 | 1575395 |
| 9 | 9316455 |
| 10 | 55211811 |
| 11 | 327600447 |
| 12 | 1945195699 |
| 13 | 11554693471 |
| 14 | 68652279747 |
| 15 | 407952680479 |
| 16 | 2424365629955 |
| 17 | 14408066169471 |
| 18 | 85629681584835 |
| 19 | 508919764066431 |
| 20 | 3024669695471107 |
[1,9,51,249,1387,7879,45663,267367,1575395, 9316455,55211811,327600447,1945195699,11554693471, 68652279747,407952680479,2424365629955, 14408066169471,85629681584835,508919764066431, 3024669695471107] |