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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 11 |
| 4 | 44 |
| 5 | 135 |
| 6 | 591 |
| 7 | 2097 |
| 8 | 9384 |
| 9 | 34617 |
| 10 | 159023 |
| 11 | 618011 |
| 12 | 2876682 |
| 13 | 11453085 |
| 14 | 53921126 |
| 15 | 219972045 |
| 16 | 1043981584 |
| 17 | 4329841785 |
| 18 | 20681051513 |
| 19 | 86993499457 |
| 20 | 417637003298 |
| 21 | 1776876347633 |
| 22 | 8565821267680 |
| 23 | 36793621788015 |
| 24 | 177982263222676 |
| 25 | 770732694642597 |
| 26 | 3739063457386497 |
| 27 | 16304891190685639 |
[1,1,4,11,44,135,591,2097,9384,34617,159023, 618011,2876682,11453085,53921126,219972045, 1043981584,4329841785,20681051513,86993499457, 417637003298,1776876347633,8565821267680, 36793621788015,177982263222676,770732694642597, 3739063457386497,16304891190685639] |