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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 64 |
| 3 | 640 |
| 4 | 6400 |
| 5 | 64000 |
| 6 | 640000 |
| 7 | 6400000 |
| 8 | 64000000 |
| 9 | 640000000 |
| 10 | 6400000000 |
| 11 | 64000000000 |
| 12 | 640000000000 |
| 13 | 6400000000000 |
| 14 | 9949906555064 |
| 15 | 64000000000000 |
| 16 | 99499065550640 |
| 17 | 99950460549564 |
| 18 | 640000000000000 |
| 19 | 969559459994564 |
| 20 | 994990655506400 |
| 21 | 999504605495640 |
[0,64,640,6400,64000,640000,6400000,64000000, 640000000,6400000000,64000000000,640000000000, 6400000000000,9949906555064,64000000000000, 99499065550640,99950460549564,640000000000000, 969559459994564,994990655506400,999504605495640] |