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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 12 |
| 4 | 39 |
| 5 | 148 |
| 6 | 550 |
| 7 | 2071 |
| 8 | 8161 |
| 9 | 32396 |
| 10 | 128707 |
| 11 | 521583 |
| 12 | 2129664 |
| 13 | 8706306 |
| 14 | 35920334 |
| 15 | 149087733 |
| 16 | 619863981 |
| 17 | 2589541208 |
| 18 | 10865234502 |
| 19 | 45674123835 |
| 20 | 192548458938 |
| 21 | 814243566145 |
| 22 | 3449403678162 |
| 23 | 14641287502016 |
| 24 | 62285013815016 |
| 25 | 265384423471876 |
| 26 | 1132421803033238 |
| 27 | 4840177356527085 |
[1,1,4,12,39,148,550,2071,8161,32396,128707, 521583,2129664,8706306,35920334,149087733, 619863981,2589541208,10865234502,45674123835, 192548458938,814243566145,3449403678162, 14641287502016,62285013815016,265384423471876, 1132421803033238,4840177356527085] |