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| n | a(n) |
|---|---|
| 1 | 4 |
| 2 | 22 |
| 3 | 101 |
| 4 | 406 |
| 5 | 1590 |
| 6 | 5866 |
| 7 | 21458 |
| 8 | 79008 |
| 9 | 279184 |
| 10 | 961538 |
| 11 | 3283383 |
| 12 | 11245705 |
| 13 | 38041395 |
| 14 | 128601451 |
| 15 | 439329246 |
| 16 | 1469925794 |
| 17 | 4882077829 |
| 18 | 16229507415 |
| 19 | 53512583955 |
| 20 | 176314746136 |
| 21 | 581275979475 |
| 22 | 1931941926271 |
| 23 | 6342886318697 |
| 24 | 20699787617422 |
| 25 | 67785725560417 |
[4,22,101,406,1590,5866,21458,79008,279184,961538, 3283383,11245705,38041395,128601451,439329246, 1469925794,4882077829,16229507415,53512583955, 176314746136,581275979475,1931941926271, 6342886318697,20699787617422,67785725560417] |