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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 2 |
| 4 | 8 |
| 5 | 17 |
| 6 | 49 |
| 7 | 128 |
| 8 | 356 |
| 9 | 983 |
| 10 | 2759 |
| 11 | 7779 |
| 12 | 22087 |
| 13 | 63000 |
| 14 | 180478 |
| 15 | 518846 |
| 16 | 1496236 |
| 17 | 4326383 |
| 18 | 12539335 |
| 19 | 36419069 |
| 20 | 105971473 |
| 21 | 308866226 |
| 22 | 901573732 |
| 23 | 2635235789 |
| 24 | 7712078755 |
| 25 | 22594899002 |
| 26 | 66266698424 |
| 27 | 194531585078 |
| 28 | 571561286576 |
| 29 | 1680679630089 |
| 30 | 4945738222801 |
[1,0,2,2,8,17,49,128,356,983,2759,7779,22087, 63000,180478,518846,1496236,4326383,12539335, 36419069,105971473,308866226,901573732,2635235789, 7712078755,22594899002,66266698424,194531585078, 571561286576,1680679630089,4945738222801] |