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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 1 |
| 5 | 2 |
| 6 | 3 |
| 7 | 7 |
| 8 | 14 |
| 9 | 33 |
| 10 | 74 |
| 11 | 180 |
| 12 | 438 |
| 13 | 1090 |
| 14 | 2741 |
| 15 | 6994 |
| 16 | 17966 |
| 17 | 46565 |
| 18 | 121440 |
| 19 | 318597 |
| 20 | 839953 |
| 21 | 2224486 |
| 22 | 5914248 |
| 23 | 15780662 |
| 24 | 42241422 |
| 25 | 113402369 |
| 26 | 305254039 |
| 27 | 823690961 |
| 28 | 2227640597 |
| 29 | 6037142355 |
| 30 | 16392945284 |
| 31 | 44592703836 |
[0,0,0,1,1,2,3,7,14,33,74,180,438,1090,2741,6994, 17966,46565,121440,318597,839953,2224486,5914248, 15780662,42241422,113402369,305254039,823690961, 2227640597,6037142355,16392945284,44592703836] |