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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 40 |
| 4 | 333 |
| 5 | 3706 |
| 6 | 52128 |
| 7 | 891700 |
| 8 | 18038217 |
| 9 | 422455778 |
| 10 | 11265993155 |
| 11 | 337573337108 |
| 12 | 11241696796572 |
| 13 | 412291622024088 |
| 14 | 16524941775629068 |
| 15 | 719072894898300540 |
| 16 | 33777207106037303457 |
| 17 | 1704222469853179505170 |
| 18 | 91954474204022335742037 |
| 19 | 5285317768791730330402208 |
[1,2,7,40,333,3706,52128,891700,18038217, 422455778,11265993155,337573337108,11241696796572, 412291622024088,16524941775629068, 719072894898300540,33777207106037303457, 1704222469853179505170,91954474204022335742037, 5285317768791730330402208] |