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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 2 |
| 2 | 2 |
| 3 | 8 |
| 4 | 18 |
| 5 | 50 |
| 6 | 128 |
| 7 | 338 |
| 8 | 882 |
| 9 | 2312 |
| 10 | 6050 |
| 11 | 15842 |
| 12 | 41472 |
| 13 | 108578 |
| 14 | 284258 |
| 15 | 744200 |
| 16 | 1948338 |
| 17 | 5100818 |
| 18 | 13354112 |
| 19 | 34961522 |
| 20 | 91530450 |
| 21 | 239629832 |
| 22 | 627359042 |
| 23 | 1642447298 |
| 24 | 4299982848 |
| 25 | 11257501250 |
| 26 | 29472520898 |
| 27 | 77160061448 |
| 28 | 202007663442 |
| 29 | 528862928882 |
| 30 | 1384581123200 |
| 31 | 3624880440722 |
| 32 | 9490060198962 |
| 33 | 24845300156168 |
| 34 | 65045840269538 |
| 35 | 170292220652450 |
| 36 | 445830821687808 |
| 37 | 1167200244410978 |
| 38 | 3055769911545122 |
| 39 | 8000109490224392 |
| 40 | 20944558559128050 |
[0,2,2,8,18,50,128,338,882,2312,6050,15842,41472, 108578,284258,744200,1948338,5100818,13354112, 34961522,91530450,239629832,627359042,1642447298, 4299982848,11257501250,29472520898,77160061448, 202007663442,528862928882,1384581123200, 3624880440722,9490060198962,24845300156168, 65045840269538,170292220652450,445830821687808, 1167200244410978,3055769911545122, 8000109490224392,20944558559128050] |