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| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 4 |
| 2 | 7 |
| 3 | 13 |
| 4 | 37 |
| 5 | 73 |
| 6 | 145 |
| 7 | 289 |
| 8 | 865 |
| 9 | 1729 |
| 10 | 3457 |
| 11 | 10369 |
| 12 | 20737 |
| 13 | 41473 |
| 14 | 82945 |
| 15 | 248833 |
| 16 | 497665 |
| 17 | 995329 |
| 18 | 1990657 |
| 19 | 3981313 |
| 20 | 11943937 |
| 21 | 23887873 |
| 22 | 47775745 |
| 23 | 143327233 |
| 24 | 286654465 |
| 25 | 573308929 |
| 26 | 1146617857 |
| 27 | 3439853569 |
| 28 | 6879707137 |
| 29 | 20639121409 |
| 30 | 41278242817 |
| 31 | 82556485633 |
[2,4,7,13,37,73,145,289,865,1729,3457,10369,20737, 41473,82945,248833,497665,995329,1990657,3981313, 11943937,23887873,47775745,143327233,286654465, 573308929,1146617857,3439853569,6879707137, 20639121409,41278242817,82556485633] |