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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 17 |
| 4 | 106 |
| 5 | 937 |
| 6 | 10886 |
| 7 | 156865 |
| 8 | 2696338 |
| 9 | 53808401 |
| 10 | 1222222222 |
| 11 | 31124909521 |
| 12 | 878100801722 |
| 13 | 27181099309561 |
| 14 | 915824738370166 |
| 15 | 33363344029017857 |
| 16 | 1306644371887759906 |
| 17 | 54743840860125227041 |
| 18 | 2443077625590307888670 |
| 19 | 115697055886568046147601 |
[1,4,17,106,937,10886,156865,2696338,53808401, 1222222222,31124909521,878100801722, 27181099309561,915824738370166,33363344029017857, 1306644371887759906,54743840860125227041, 2443077625590307888670,115697055886568046147601] |