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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 20 |
| 2 | 21 |
| 3 | 62 |
| 4 | 393 |
| 5 | 455 |
| 6 | 848 |
| 7 | 2999 |
| 8 | 3847 |
| 9 | 6846 |
| 10 | 10693 |
| 11 | 17539 |
| 12 | 203622 |
| 13 | 221161 |
| 14 | 1088266 |
| 15 | 3485959 |
| 16 | 4574225 |
| 17 | 67525109 |
| 18 | 72099334 |
| 19 | 283823111 |
| 20 | 1207391778 |
| 21 | 1491214889 |
| 22 | 17610755557 |
| 23 | 19101970446 |
| 24 | 36712726003 |
| 25 | 55814696449 |
| 26 | 92527422452 |
| 27 | 333396963805 |
| 28 | 425924386257 |
[1,20,21,62,393,455,848,2999,3847,6846,10693, 17539,203622,221161,1088266,3485959,4574225, 67525109,72099334,283823111,1207391778,1491214889, 17610755557,19101970446,36712726003,55814696449, 92527422452,333396963805,425924386257] |