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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 6 |
| 4 | 17 |
| 5 | 42 |
| 6 | 118 |
| 7 | 320 |
| 8 | 861 |
| 9 | 2442 |
| 10 | 6658 |
| 11 | 18686 |
| 12 | 52100 |
| 13 | 146832 |
| 14 | 410990 |
| 15 | 1161722 |
| 16 | 3282403 |
| 17 | 9283968 |
| 18 | 26336598 |
| 19 | 74712158 |
| 20 | 212613094 |
| 21 | 605118528 |
| 22 | 1726261816 |
| 23 | 4926677982 |
| 24 | 14079210098 |
| 25 | 40247549662 |
| 26 | 115175011608 |
| 27 | 329707161766 |
| 28 | 944566633454 |
| 29 | 2707713181042 |
[1,1,3,6,17,42,118,320,861,2442,6658,18686,52100, 146832,410990,1161722,3282403,9283968,26336598, 74712158,212613094,605118528,1726261816, 4926677982,14079210098,40247549662,115175011608, 329707161766,944566633454,2707713181042] |