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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 21 |
| 5 | 73 |
| 6 | 241 |
| 7 | 754 |
| 8 | 2252 |
| 9 | 6471 |
| 10 | 18003 |
| 11 | 48736 |
| 12 | 128878 |
| 13 | 333949 |
| 14 | 850061 |
| 15 | 2130078 |
| 16 | 5263536 |
| 17 | 12845251 |
| 18 | 30998743 |
| 19 | 74055916 |
| 20 | 175309058 |
| 21 | 411566361 |
| 22 | 958923057 |
| 23 | 2218787146 |
| 24 | 5101322596 |
| 25 | 11660165503 |
| 26 | 26508001691 |
| 27 | 59961770424 |
| 28 | 135006257622 |
| 29 | 302660977141 |
| 30 | 675786261013 |
| 31 | 1503238554166 |
| 32 | 3332089315928 |
[1,1,2,6,21,73,241,754,2252,6471,18003,48736, 128878,333949,850061,2130078,5263536,12845251, 30998743,74055916,175309058,411566361,958923057, 2218787146,5101322596,11660165503,26508001691, 59961770424,135006257622,302660977141, 675786261013,1503238554166,3332089315928] |