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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 25 |
| 5 | 67 |
| 6 | 176 |
| 7 | 453 |
| 8 | 1149 |
| 9 | 2882 |
| 10 | 7161 |
| 11 | 17654 |
| 12 | 43238 |
| 13 | 105303 |
| 14 | 255210 |
| 15 | 615896 |
| 16 | 1480771 |
| 17 | 3548313 |
| 18 | 8477415 |
| 19 | 20199596 |
| 20 | 48014369 |
| 21 | 113879450 |
| 22 | 269555798 |
| 23 | 636875077 |
| 24 | 1502195104 |
| 25 | 3537705916 |
| 26 | 8319377813 |
| 27 | 19537936874 |
| 28 | 45827441193 |
| 29 | 107366261405 |
| 30 | 251268532266 |
[0,1,3,9,25,67,176,453,1149,2882,7161,17654,43238, 105303,255210,615896,1480771,3548313,8477415, 20199596,48014369,113879450,269555798,636875077, 1502195104,3537705916,8319377813,19537936874, 45827441193,107366261405,251268532266] |