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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 16 |
| 5 | 44 |
| 6 | 122 |
| 7 | 341 |
| 8 | 940 |
| 9 | 2581 |
| 10 | 7064 |
| 11 | 19258 |
| 12 | 52348 |
| 13 | 141935 |
| 14 | 383962 |
| 15 | 1036633 |
| 16 | 2793812 |
| 17 | 7517698 |
| 18 | 20200330 |
| 19 | 54209775 |
| 20 | 145309380 |
| 21 | 389091111 |
| 22 | 1040853492 |
| 23 | 2781908250 |
| 24 | 7429184976 |
| 25 | 19824925429 |
| 26 | 52866176702 |
| 27 | 140883978971 |
| 28 | 375216491080 |
[0,1,2,5,16,44,122,341,940,2581,7064,19258,52348, 141935,383962,1036633,2793812,7517698,20200330, 54209775,145309380,389091111,1040853492, 2781908250,7429184976,19824925429,52866176702, 140883978971,375216491080] |