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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 10 |
| 3 | 20 |
| 4 | 52 |
| 5 | 179 |
| 6 | 418 |
| 7 | 1167 |
| 8 | 3498 |
| 9 | 9074 |
| 10 | 25737 |
| 11 | 72785 |
| 12 | 196688 |
| 13 | 553939 |
| 14 | 1545841 |
| 15 | 4257959 |
| 16 | 11909122 |
| 17 | 33092586 |
| 18 | 91740852 |
| 19 | 255765150 |
| 20 | 710642687 |
| 21 | 1974282820 |
| 22 | 5494583699 |
| 23 | 15269944796 |
| 24 | 42450687178 |
| 25 | 118071427215 |
| 26 | 328208378089 |
| 27 | 912542015410 |
| 28 | 2537483145585 |
| 29 | 7054481803595 |
[1,2,10,20,52,179,418,1167,3498,9074,25737,72785, 196688,553939,1545841,4257959,11909122,33092586, 91740852,255765150,710642687,1974282820, 5494583699,15269944796,42450687178,118071427215, 328208378089,912542015410,2537483145585, 7054481803595] |