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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 7 |
| 5 | 23 |
| 6 | 55 |
| 7 | 164 |
| 8 | 407 |
| 9 | 1235 |
| 10 | 3051 |
| 11 | 9432 |
| 12 | 23431 |
| 13 | 72989 |
| 14 | 182624 |
| 15 | 571384 |
| 16 | 1436855 |
| 17 | 4511979 |
| 18 | 11387467 |
| 19 | 35866100 |
| 20 | 90782837 |
| 21 | 286622226 |
| 22 | 727226578 |
| 23 | 2300578392 |
| 24 | 5848776767 |
| 25 | 18533394763 |
| 26 | 47197285045 |
| 27 | 149769168304 |
| 28 | 381956145802 |
| 29 | 1213526310665 |
| 30 | 3098742448230 |
[1,1,1,4,7,23,55,164,407,1235,3051,9432,23431, 72989,182624,571384,1436855,4511979,11387467, 35866100,90782837,286622226,727226578,2300578392, 5848776767,18533394763,47197285045,149769168304, 381956145802,1213526310665,3098742448230] |