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| n | a(n) |
|---|---|
| 1 | 21 |
| 2 | 42 |
| 3 | 84 |
| 4 | 85 |
| 5 | 168 |
| 6 | 170 |
| 7 | 336 |
| 8 | 340 |
| 9 | 341 |
| 10 | 453 |
| 11 | 672 |
| 12 | 680 |
| 13 | 682 |
| 14 | 906 |
| 15 | 909 |
| 16 | 1344 |
| 17 | 1360 |
| 18 | 1364 |
| 19 | 1365 |
| 20 | 1812 |
| 21 | 1813 |
| 22 | 1818 |
| 23 | 2688 |
| 24 | 2720 |
| 25 | 2728 |
| 26 | 2730 |
| 27 | 3624 |
| 28 | 3626 |
| 29 | 3636 |
| 30 | 5376 |
| 31 | 5440 |
| 32 | 5456 |
| 33 | 5460 |
| 34 | 5461 |
| 35 | 7248 |
| 36 | 7252 |
| 37 | 7272 |
| 38 | 7281 |
| 39 | 9669 |
[21,42,84,85,168,170,336,340,341,453,672,680,682, 906,909,1344,1360,1364,1365,1812,1813,1818,2688, 2720,2728,2730,3624,3626,3636,5376,5440,5456,5460, 5461,7248,7252,7272,7281,9669] |