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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 14 |
| 5 | 50 |
| 6 | 199 |
| 7 | 749 |
| 8 | 2892 |
| 9 | 11028 |
| 10 | 42301 |
| 11 | 161799 |
| 12 | 619706 |
| 13 | 2372006 |
| 14 | 9081955 |
| 15 | 34767953 |
| 16 | 133109592 |
| 17 | 509594856 |
| 18 | 1950956857 |
| 19 | 7469077707 |
| 20 | 28594853414 |
| 21 | 109473250778 |
| 22 | 419110475455 |
| 23 | 1604533706357 |
| 24 | 6142840740900 |
| 25 | 23517417426300 |
[0,0,1,3,14,50,199,749,2892,11028,42301,161799, 619706,2372006,9081955,34767953,133109592, 509594856,1950956857,7469077707,28594853414, 109473250778,419110475455,1604533706357, 6142840740900,23517417426300] |