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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 11 |
| 4 | 36 |
| 5 | 125 |
| 6 | 435 |
| 7 | 1595 |
| 8 | 5954 |
| 9 | 22465 |
| 10 | 86223 |
| 11 | 334795 |
| 12 | 1315848 |
| 13 | 5206019 |
| 14 | 20773532 |
| 15 | 83318857 |
| 16 | 336730400 |
| 17 | 1367649633 |
| 18 | 5578371219 |
| 19 | 22851417683 |
| 20 | 93958046678 |
| 21 | 387906668755 |
| 22 | 1606184507258 |
| 23 | 6669799558525 |
| 24 | 27769835689296 |
| 25 | 115931233180053 |
| 26 | 485172793681327 |
| 27 | 2034581806716141 |
| 28 | 8549095477414610 |
[1,1,4,11,36,125,435,1595,5954,22465,86223,334795, 1315848,5206019,20773532,83318857,336730400, 1367649633,5578371219,22851417683,93958046678, 387906668755,1606184507258,6669799558525, 27769835689296,115931233180053,485172793681327, 2034581806716141,8549095477414610] |