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| n | a(n) |
|---|---|
| 4 | 1 |
| 5 | 2 |
| 6 | 9 |
| 7 | 28 |
| 8 | 93 |
| 9 | 294 |
| 10 | 925 |
| 11 | 2872 |
| 12 | 8856 |
| 13 | 27136 |
| 14 | 82764 |
| 15 | 251472 |
| 16 | 761774 |
| 17 | 2301924 |
| 18 | 6941898 |
| 19 | 20899680 |
| 20 | 62834397 |
| 21 | 188690634 |
| 22 | 566081421 |
| 23 | 1696873148 |
| 24 | 5082959517 |
| 25 | 15216909686 |
| 26 | 45532045749 |
| 27 | 136182428520 |
| 28 | 407160436435 |
| 29 | 1216953379486 |
| 30 | 3636353333187 |
[1,2,9,28,93,294,925,2872,8856,27136,82764,251472, 761774,2301924,6941898,20899680,62834397, 188690634,566081421,1696873148,5082959517, 15216909686,45532045749,136182428520,407160436435, 1216953379486,3636353333187] |