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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 16 |
| 5 | 57 |
| 6 | 226 |
| 7 | 961 |
| 8 | 4376 |
| 9 | 21041 |
| 10 | 106534 |
| 11 | 563961 |
| 12 | 3112924 |
| 13 | 17839993 |
| 14 | 105907946 |
| 15 | 649432673 |
| 16 | 4105783696 |
| 17 | 26706965985 |
| 18 | 178466243662 |
| 19 | 1223248786921 |
| 20 | 8589272300516 |
| 21 | 61708802126441 |
| 22 | 453143009601682 |
| 23 | 3397715981566545 |
| 24 | 25990997059282456 |
| 25 | 202666687407866257 |
[1,1,2,5,16,57,226,961,4376,21041,106534,563961, 3112924,17839993,105907946,649432673,4105783696, 26706965985,178466243662,1223248786921, 8589272300516,61708802126441,453143009601682, 3397715981566545,25990997059282456, 202666687407866257] |