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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 10 |
| 5 | 23 |
| 6 | 63 |
| 7 | 155 |
| 8 | 448 |
| 9 | 1152 |
| 10 | 3451 |
| 11 | 9156 |
| 12 | 28155 |
| 13 | 76491 |
| 14 | 240015 |
| 15 | 664363 |
| 16 | 2118804 |
| 17 | 5954414 |
| 18 | 19246816 |
| 19 | 54772539 |
| 20 | 179063855 |
| 21 | 515006165 |
| 22 | 1700131496 |
| 23 | 4934242781 |
| 24 | 16427135058 |
| 25 | 48050970367 |
| 26 | 161163698861 |
| 27 | 474656662565 |
| 28 | 1602509174036 |
| 29 | 4748224219223 |
| 30 | 16125057102402 |
[1,1,2,4,10,23,63,155,448,1152,3451,9156,28155, 76491,240015,664363,2118804,5954414,19246816, 54772539,179063855,515006165,1700131496, 4934242781,16427135058,48050970367,161163698861, 474656662565,1602509174036,4748224219223, 16125057102402] |