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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 9 |
| 4 | 40 |
| 5 | 114 |
| 6 | 528 |
| 7 | 1703 |
| 8 | 8060 |
| 9 | 28046 |
| 10 | 134504 |
| 11 | 492714 |
| 12 | 2383928 |
| 13 | 9063508 |
| 14 | 44127320 |
| 15 | 172559091 |
| 16 | 844018252 |
| 17 | 3374183038 |
| 18 | 16561875136 |
| 19 | 67397982670 |
| 20 | 331727733384 |
| 21 | 1369846371868 |
| 22 | 6757092675160 |
| 23 | 28246826894110 |
| 24 | 139582693099384 |
| 25 | 589605775705292 |
| 26 | 2917837189521072 |
| 27 | 12435985878882788 |
| 28 | 61618484473063792 |
[1,1,4,9,40,114,528,1703,8060,28046,134504,492714, 2383928,9063508,44127320,172559091,844018252, 3374183038,16561875136,67397982670,331727733384, 1369846371868,6757092675160,28246826894110, 139582693099384,589605775705292,2917837189521072, 12435985878882788,61618484473063792] |