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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 4 |
| 4 | 11 |
| 5 | 30 |
| 6 | 83 |
| 7 | 232 |
| 8 | 655 |
| 9 | 1860 |
| 10 | 5312 |
| 11 | 15236 |
| 12 | 43863 |
| 13 | 126672 |
| 14 | 366802 |
| 15 | 1064624 |
| 16 | 3096347 |
| 17 | 9021696 |
| 18 | 26328470 |
| 19 | 76946524 |
| 20 | 225172981 |
| 21 | 659711646 |
| 22 | 1934891191 |
| 23 | 5680457960 |
| 24 | 16691655761 |
| 25 | 49087826580 |
| 26 | 144470474228 |
| 27 | 425491536172 |
| 28 | 1253971031195 |
| 29 | 3697850012310 |
[1,0,2,4,11,30,83,232,655,1860,5312,15236,43863, 126672,366802,1064624,3096347,9021696,26328470, 76946524,225172981,659711646,1934891191, 5680457960,16691655761,49087826580,144470474228, 425491536172,1253971031195,3697850012310] |