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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 2 |
| 3 | 2 |
| 4 | 4 |
| 5 | 10 |
| 6 | 24 |
| 7 | 56 |
| 8 | 142 |
| 9 | 346 |
| 10 | 874 |
| 11 | 2210 |
| 12 | 5640 |
| 13 | 14440 |
| 14 | 37224 |
| 15 | 96128 |
| 16 | 249108 |
| 17 | 646710 |
| 18 | 1681772 |
| 19 | 4378614 |
| 20 | 11411374 |
| 21 | 29760404 |
| 22 | 77658384 |
| 23 | 202729956 |
| 24 | 529406180 |
| 25 | 1382821596 |
| 26 | 3612643922 |
| 27 | 9439431124 |
| 28 | 24666860228 |
| 29 | 64464076954 |
| 30 | 168480273482 |
[0,2,2,4,10,24,56,142,346,874,2210,5640,14440, 37224,96128,249108,646710,1681772,4378614, 11411374,29760404,77658384,202729956,529406180, 1382821596,3612643922,9439431124,24666860228, 64464076954,168480273482] |