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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 4 |
| 5 | 7 |
| 6 | 13 |
| 7 | 23 |
| 8 | 40 |
| 9 | 74 |
| 10 | 148 |
| 11 | 263 |
| 12 | 493 |
| 13 | 934 |
| 14 | 1719 |
| 15 | 3192 |
| 16 | 6035 |
| 17 | 11280 |
| 18 | 21252 |
| 19 | 40367 |
| 20 | 75796 |
[1,1,1,3,4,7,13,23,40,74,148,263,493,934,1719, 3192,6035,11280,21252,40367,75796] |