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A271894 as a simple table
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 3 |
| 2 | 7 |
| 3 | 20 |
| 4 | 50 |
| 5 | 138 |
| 6 | 356 |
| 7 | 964 |
| 8 | 2524 |
| 9 | 6768 |
| 10 | 17848 |
| 11 | 47624 |
| 12 | 126032 |
| 13 | 335472 |
| 14 | 889328 |
| 15 | 2364352 |
| 16 | 6273184 |
| 17 | 16667808 |
| 18 | 44242240 |
| 19 | 117516608 |
| 20 | 311995328 |
| 21 | 828603648 |
| 22 | 2200088960 |
| 23 | 5842620544 |
| 24 | 15513975040 |
| 25 | 41197898496 |
| 26 | 109395973888 |
| 27 | 290499691520 |
| 28 | 771395887616 |
[1,3,7,20,50,138,356,964,2524,6768,17848,47624, 126032,335472,889328,2364352,6273184,16667808, 44242240,117516608,311995328,828603648,2200088960, 5842620544,15513975040,41197898496,109395973888, 290499691520,771395887616] |