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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 4 |
| 4 | 17 |
| 5 | 62 |
| 6 | 255 |
| 7 | 1026 |
| 8 | 4363 |
| 9 | 18656 |
| 10 | 81446 |
| 11 | 357708 |
| 12 | 1584110 |
| 13 | 7042396 |
| 14 | 31429998 |
| 15 | 140626375 |
| 16 | 630640342 |
| 17 | 2833200433 |
| 18 | 12748771157 |
| 19 | 57445747751 |
| 20 | 259170739397 |
| 21 | 1170566884224 |
| 22 | 5292311737901 |
| 23 | 23949417255984 |
| 24 | 108470668735077 |
| 25 | 491664303153769 |
| 26 | 2230174016940385 |
| 27 | 10122784007130716 |
[0,1,4,17,62,255,1026,4363,18656,81446,357708, 1584110,7042396,31429998,140626375,630640342, 2833200433,12748771157,57445747751,259170739397, 1170566884224,5292311737901,23949417255984, 108470668735077,491664303153769,2230174016940385, 10122784007130716] |