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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 2 |
| 5 | 10 |
| 6 | 57 |
| 7 | 279 |
| 8 | 1338 |
| 9 | 6329 |
| 10 | 29969 |
| 11 | 142461 |
| 12 | 680637 |
| 13 | 3269716 |
| 14 | 15785281 |
| 15 | 76557773 |
| 16 | 372812193 |
| 17 | 1822122394 |
| 18 | 8934639920 |
| 19 | 43938614933 |
| 20 | 216649723022 |
| 21 | 1070790651782 |
| 22 | 5303849549438 |
| 23 | 26323051151997 |
| 24 | 130878360554692 |
| 25 | 651812916543553 |
| 26 | 3251215337590494 |
| 27 | 16240020424411300 |
| 28 | 81227146998545009 |
| 29 | 406770969279959357 |
| 30 | 2039375194931563287 |
[0,0,0,2,10,57,279,1338,6329,29969,142461,680637, 3269716,15785281,76557773,372812193,1822122394, 8934639920,43938614933,216649723022,1070790651782, 5303849549438,26323051151997,130878360554692, 651812916543553,3251215337590494, 16240020424411300,81227146998545009, 406770969279959357,2039375194931563287] |