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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 21 |
| 5 | 78 |
| 6 | 298 |
| 7 | 1157 |
| 8 | 4539 |
| 9 | 17936 |
| 10 | 71251 |
| 11 | 284188 |
| 12 | 1137076 |
| 13 | 4561093 |
| 14 | 18333337 |
| 15 | 73816489 |
| 16 | 297635750 |
| 17 | 1201551286 |
| 18 | 4855672249 |
| 19 | 19640147061 |
| 20 | 79501958895 |
| 21 | 322037615290 |
| 22 | 1305256267511 |
| 23 | 5293166568270 |
| 24 | 21475362822956 |
| 25 | 87166344495561 |
| 26 | 353933533606927 |
[1,1,2,6,21,78,298,1157,4539,17936,71251,284188, 1137076,4561093,18333337,73816489,297635750, 1201551286,4855672249,19640147061,79501958895, 322037615290,1305256267511,5293166568270, 21475362822956,87166344495561,353933533606927] |