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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 10 |
| 4 | 40 |
| 5 | 129 |
| 6 | 549 |
| 7 | 1933 |
| 8 | 8502 |
| 9 | 31708 |
| 10 | 142109 |
| 11 | 549108 |
| 12 | 2494264 |
| 13 | 9891529 |
| 14 | 45352455 |
| 15 | 183421419 |
| 16 | 847068443 |
| 17 | 3478366440 |
| 18 | 16154265409 |
| 19 | 67150019188 |
| 20 | 313261541733 |
| 21 | 1315277095648 |
| 22 | 6158394389696 |
| 23 | 26075273852257 |
| 24 | 122461840619532 |
| 25 | 522243214701570 |
| 26 | 2459029674132398 |
| 27 | 10551608705702006 |
[1,1,4,10,40,129,549,1933,8502,31708,142109, 549108,2494264,9891529,45352455,183421419, 847068443,3478366440,16154265409,67150019188, 313261541733,1315277095648,6158394389696, 26075273852257,122461840619532,522243214701570, 2459029674132398,10551608705702006] |