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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 2 |
| 5 | 6 |
| 6 | 12 |
| 7 | 32 |
| 8 | 73 |
| 9 | 180 |
| 10 | 426 |
| 11 | 1041 |
| 12 | 2507 |
| 13 | 6113 |
| 14 | 14853 |
| 15 | 36283 |
| 16 | 88622 |
| 17 | 217054 |
| 18 | 532018 |
| 19 | 1306281 |
| 20 | 3210392 |
| 21 | 7899770 |
| 22 | 19456524 |
| 23 | 47966169 |
| 24 | 118346672 |
| 25 | 292228449 |
| 26 | 722098114 |
| 27 | 1785513052 |
| 28 | 4417719597 |
| 29 | 10936705897 |
[0,0,1,2,6,12,32,73,180,426,1041,2507,6113,14853, 36283,88622,217054,532018,1306281,3210392,7899770, 19456524,47966169,118346672,292228449,722098114, 1785513052,4417719597,10936705897] |