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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 11 |
| 3 | 32 |
| 4 | 94 |
| 5 | 272 |
| 6 | 786 |
| 7 | 2272 |
| 8 | 6564 |
| 9 | 18962 |
| 10 | 54780 |
| 11 | 158254 |
| 12 | 457174 |
| 13 | 1320712 |
| 14 | 3815354 |
| 15 | 11022024 |
| 16 | 31841080 |
| 17 | 91984410 |
| 18 | 265730044 |
| 19 | 767656774 |
| 20 | 2217652596 |
| 21 | 6406486864 |
| 22 | 18507440702 |
| 23 | 53465396640 |
| 24 | 154454021166 |
| 25 | 446195972602 |
| 26 | 1288997492332 |
| 27 | 3723732703246 |
[1,4,11,32,94,272,786,2272,6564,18962,54780, 158254,457174,1320712,3815354,11022024,31841080, 91984410,265730044,767656774,2217652596, 6406486864,18507440702,53465396640,154454021166, 446195972602,1288997492332,3723732703246] |