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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 15 |
| 4 | 48 |
| 5 | 160 |
| 6 | 548 |
| 7 | 1914 |
| 8 | 6785 |
| 9 | 24335 |
| 10 | 88109 |
| 11 | 321521 |
| 12 | 1181039 |
| 13 | 4362855 |
| 14 | 16195747 |
| 15 | 60379623 |
| 16 | 225955264 |
| 17 | 848432824 |
| 18 | 3195394520 |
| 19 | 12067450014 |
| 20 | 45685766306 |
| 21 | 173350890788 |
| 22 | 659126407978 |
| 23 | 2510942564760 |
| 24 | 9582235262428 |
| 25 | 36627111558850 |
| 26 | 140214938146148 |
[1,2,5,15,48,160,548,1914,6785,24335,88109,321521, 1181039,4362855,16195747,60379623,225955264, 848432824,3195394520,12067450014,45685766306, 173350890788,659126407978,2510942564760, 9582235262428,36627111558850,140214938146148] |