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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 28 |
| 4 | 112 |
| 5 | 441 |
| 6 | 1715 |
| 7 | 6615 |
| 8 | 25382 |
| 9 | 97069 |
| 10 | 370440 |
| 11 | 1411788 |
| 12 | 5375839 |
| 13 | 20458921 |
| 14 | 77833217 |
| 15 | 296038498 |
| 16 | 1125816895 |
| 17 | 4281011812 |
| 18 | 16277915640 |
| 19 | 61891962377 |
| 20 | 235320000363 |
| 21 | 894697938743 |
| 22 | 3401649302758 |
| 23 | 12933013979445 |
| 24 | 49170893188704 |
| 25 | 186945601728004 |
| 26 | 710757805310287 |
[1,2,7,28,112,441,1715,6615,25382,97069,370440, 1411788,5375839,20458921,77833217,296038498, 1125816895,4281011812,16277915640,61891962377, 235320000363,894697938743,3401649302758, 12933013979445,49170893188704,186945601728004, 710757805310287] |