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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 12 |
| 4 | 46 |
| 5 | 177 |
| 6 | 681 |
| 7 | 2620 |
| 8 | 10080 |
| 9 | 38781 |
| 10 | 149203 |
| 11 | 574032 |
| 12 | 2208486 |
| 13 | 8496757 |
| 14 | 32689761 |
| 15 | 125768040 |
| 16 | 483870160 |
| 17 | 1861604361 |
| 18 | 7162191603 |
| 19 | 27555258052 |
| 20 | 106013953326 |
| 21 | 407869825737 |
| 22 | 1569206595241 |
| 23 | 6037243216260 |
| 24 | 23227219260240 |
| 25 | 89362594024741 |
| 26 | 343806683071203 |
[0,1,3,12,46,177,681,2620,10080,38781,149203, 574032,2208486,8496757,32689761,125768040, 483870160,1861604361,7162191603,27555258052, 106013953326,407869825737,1569206595241, 6037243216260,23227219260240,89362594024741, 343806683071203] |