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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 0 |
| 4 | 2 |
| 5 | 2 |
| 6 | 5 |
| 7 | 8 |
| 8 | 18 |
| 9 | 30 |
| 10 | 66 |
| 11 | 120 |
| 12 | 252 |
| 13 | 484 |
| 14 | 1005 |
| 15 | 1984 |
| 16 | 4110 |
| 17 | 8278 |
| 18 | 17150 |
| 19 | 35024 |
| 20 | 72748 |
| 21 | 150012 |
| 22 | 312642 |
| 23 | 649424 |
| 24 | 1358244 |
| 25 | 2837484 |
| 26 | 5954980 |
| 27 | 12497616 |
| 28 | 26313432 |
| 29 | 55434248 |
| 30 | 117062205 |
| 31 | 247412928 |
| 32 | 523881238 |
| 33 | 1110335334 |
| 34 | 2356819254 |
| 35 | 5007428384 |
| 36 | 10652412108 |
| 37 | 22682131308 |
| 38 | 48349084054 |
| 39 | 103150869360 |
| 40 | 220276819836 |
[1,0,1,0,2,2,5,8,18,30,66,120,252,484,1005,1984, 4110,8278,17150,35024,72748,150012,312642,649424, 1358244,2837484,5954980,12497616,26313432, 55434248,117062205,247412928,523881238,1110335334, 2356819254,5007428384,10652412108,22682131308, 48349084054,103150869360,220276819836] |