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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 7 |
| 3 | 26 |
| 4 | 78 |
| 5 | 211 |
| 6 | 537 |
| 7 | 1312 |
| 8 | 3112 |
| 9 | 7217 |
| 10 | 16443 |
| 11 | 36934 |
| 12 | 82002 |
| 13 | 180319 |
| 14 | 393325 |
| 15 | 852092 |
| 16 | 1835148 |
| 17 | 3932317 |
| 18 | 8388783 |
| 19 | 17825986 |
| 20 | 37748950 |
| 21 | 79692011 |
| 22 | 167772417 |
| 23 | 352321816 |
| 24 | 738197808 |
| 25 | 1543504201 |
| 26 | 3221225827 |
| 27 | 6710886782 |
| 28 | 13958644122 |
[1,7,26,78,211,537,1312,3112,7217,16443,36934, 82002,180319,393325,852092,1835148,3932317, 8388783,17825986,37748950,79692011,167772417, 352321816,738197808,1543504201,3221225827, 6710886782,13958644122] |