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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 24 |
| 4 | 90 |
| 5 | 365 |
| 6 | 1376 |
| 7 | 5272 |
| 8 | 20098 |
| 9 | 77016 |
| 10 | 295836 |
| 11 | 1139834 |
| 12 | 4402490 |
| 13 | 17042341 |
| 14 | 66101848 |
| 15 | 256838544 |
| 16 | 999512058 |
| 17 | 3895191476 |
| 18 | 15199297796 |
| 19 | 59377405654 |
| 20 | 232208188726 |
| 21 | 908978576496 |
| 22 | 3561356276424 |
| 23 | 13964734085774 |
| 24 | 54799750800530 |
| 25 | 215193550759630 |
| 26 | 845596666261036 |
[1,4,24,90,365,1376,5272,20098,77016,295836, 1139834,4402490,17042341,66101848,256838544, 999512058,3895191476,15199297796,59377405654, 232208188726,908978576496,3561356276424, 13964734085774,54799750800530,215193550759630, 845596666261036] |