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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 5 |
| 4 | 11 |
| 5 | 36 |
| 6 | 95 |
| 7 | 281 |
| 8 | 781 |
| 9 | 2245 |
| 10 | 6336 |
| 11 | 18061 |
| 12 | 51205 |
| 13 | 145601 |
| 14 | 413351 |
| 15 | 1174500 |
| 16 | 3335651 |
| 17 | 9475901 |
| 18 | 26915305 |
| 19 | 76455961 |
| 20 | 217172736 |
| 21 | 616891945 |
| 22 | 1752296281 |
| 23 | 4977472781 |
| 24 | 14138673395 |
| 25 | 40161441636 |
| 26 | 114079985111 |
| 27 | 324048393905 |
[0,1,1,5,11,36,95,281,781,2245,6336,18061,51205, 145601,413351,1174500,3335651,9475901,26915305, 76455961,217172736,616891945,1752296281, 4977472781,14138673395,40161441636,114079985111, 324048393905] |