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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 12 |
| 5 | 28 |
| 6 | 91 |
| 7 | 247 |
| 8 | 877 |
| 9 | 2567 |
| 10 | 9614 |
| 11 | 29933 |
| 12 | 116257 |
| 13 | 378638 |
| 14 | 1514149 |
| 15 | 5106545 |
| 16 | 20883108 |
| 17 | 72470751 |
| 18 | 301746422 |
| 19 | 1072034351 |
| 20 | 4530557200 |
| 21 | 16417140603 |
| 22 | 70249343442 |
| 23 | 258899615482 |
| 24 | 1119612561509 |
| 25 | 4187069695975 |
| 26 | 18272653982056 |
| 27 | 69215461294551 |
| 28 | 304463707987332 |
| 29 | 1166400842622832 |
| 30 | 5166572419820000 |
[1,1,2,4,12,28,91,247,877,2567,9614,29933,116257, 378638,1514149,5106545,20883108,72470751, 301746422,1072034351,4530557200,16417140603, 70249343442,258899615482,1119612561509, 4187069695975,18272653982056,69215461294551, 304463707987332,1166400842622832,5166572419820000] |