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| n | a(n) |
|---|---|
| 1 | 21 |
| 2 | 51 |
| 3 | 106 |
| 4 | 211 |
| 5 | 416 |
| 6 | 821 |
| 7 | 1626 |
| 8 | 3231 |
| 9 | 6411 |
| 10 | 12716 |
| 11 | 25221 |
| 12 | 50026 |
| 13 | 99231 |
| 14 | 196836 |
| 15 | 390441 |
| 16 | 774471 |
| 17 | 1536226 |
| 18 | 3047231 |
| 19 | 6044436 |
| 20 | 11989641 |
| 21 | 23782446 |
| 22 | 47174451 |
| 23 | 93574431 |
| 24 | 185612636 |
| 25 | 368178041 |
| 26 | 730311646 |
| 27 | 1448633651 |
| 28 | 2873484856 |
| 29 | 5699795261 |
[21,51,106,211,416,821,1626,3231,6411,12716,25221, 50026,99231,196836,390441,774471,1536226,3047231, 6044436,11989641,23782446,47174451,93574431, 185612636,368178041,730311646,1448633651, 2873484856,5699795261] |