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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 11 |
| 4 | 44 |
| 5 | 167 |
| 6 | 688 |
| 7 | 2890 |
| 8 | 12419 |
| 9 | 54454 |
| 10 | 241769 |
| 11 | 1087412 |
| 12 | 4935565 |
| 13 | 22595510 |
| 14 | 104165606 |
| 15 | 483135030 |
| 16 | 2252977513 |
| 17 | 10554133201 |
| 18 | 49650073966 |
| 19 | 234409724447 |
| 20 | 1110396592564 |
| 21 | 5275286144880 |
| 22 | 25129241775010 |
| 23 | 119993639461761 |
| 24 | 574241452799050 |
| 25 | 2753632778141387 |
| 26 | 13228721517683888 |
| 27 | 63660517124775179 |
[1,1,4,11,44,167,688,2890,12419,54454,241769, 1087412,4935565,22595510,104165606,483135030, 2252977513,10554133201,49650073966,234409724447, 1110396592564,5275286144880,25129241775010, 119993639461761,574241452799050,2753632778141387, 13228721517683888,63660517124775179] |