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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 6 |
| 3 | 14 |
| 4 | 31 |
| 5 | 70 |
| 6 | 157 |
| 7 | 353 |
| 8 | 793 |
| 9 | 1782 |
| 10 | 4004 |
| 11 | 8997 |
| 12 | 20216 |
| 13 | 45425 |
| 14 | 102069 |
| 15 | 229347 |
| 16 | 515338 |
| 17 | 1157954 |
| 18 | 2601899 |
| 19 | 5846414 |
| 20 | 13136773 |
| 21 | 29518061 |
| 22 | 66326481 |
| 23 | 149034250 |
| 24 | 334876920 |
| 25 | 752461609 |
| 26 | 1690765888 |
| 27 | 3799116465 |
| 28 | 8536537209 |
| 29 | 19181424995 |
[1,3,6,14,31,70,157,353,793,1782,4004,8997,20216, 45425,102069,229347,515338,1157954,2601899, 5846414,13136773,29518061,66326481,149034250, 334876920,752461609,1690765888,3799116465, 8536537209,19181424995] |