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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 7 |
| 2 | 57 |
| 3 | 495 |
| 4 | 4401 |
| 5 | 39447 |
| 6 | 354537 |
| 7 | 3189375 |
| 8 | 28700001 |
| 9 | 258286887 |
| 10 | 2324542617 |
| 11 | 20920765455 |
| 12 | 188286534801 |
| 13 | 1694577750327 |
| 14 | 15251196564297 |
| 15 | 137260759512735 |
| 16 | 1235346806916801 |
| 17 | 11118121176157767 |
| 18 | 100063090327139577 |
| 19 | 900567812169415215 |
[1,7,57,495,4401,39447,354537,3189375,28700001, 258286887,2324542617,20920765455,188286534801, 1694577750327,15251196564297,137260759512735, 1235346806916801,11118121176157767, 100063090327139577,900567812169415215] |