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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 6 |
| 6 | 17 |
| 7 | 43 |
| 8 | 135 |
| 9 | 536 |
| 10 | 2262 |
| 11 | 9109 |
| 12 | 40119 |
| 13 | 198069 |
| 14 | 1057149 |
| 15 | 5656915 |
| 16 | 31937212 |
| 17 | 191032078 |
| 18 | 1218669125 |
| 19 | 7948119483 |
| 20 | 54117500635 |
| 21 | 381631039690 |
| 22 | 2828205076600 |
| 23 | 21507011811289 |
| 24 | 169880627954541 |
| 25 | 1377653319819302 |
| 26 | 11620433411120653 |
| 27 | 100417638302823210 |
[1,1,1,1,2,6,17,43,135,536,2262,9109,40119,198069, 1057149,5656915,31937212,191032078,1218669125, 7948119483,54117500635,381631039690,2828205076600, 21507011811289,169880627954541,1377653319819302, 11620433411120653,100417638302823210] |