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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 7 |
| 3 | 25 |
| 4 | 86 |
| 5 | 269 |
| 6 | 862 |
| 7 | 2606 |
| 8 | 7812 |
| 9 | 22704 |
| 10 | 64989 |
| 11 | 182356 |
| 12 | 504414 |
| 13 | 1373694 |
| 14 | 3693367 |
| 15 | 9804435 |
| 16 | 25733084 |
| 17 | 66808578 |
| 18 | 171719539 |
| 19 | 437183839 |
| 20 | 1103143657 |
| 21 | 2760037810 |
| 22 | 6850400668 |
| 23 | 16873338215 |
| 24 | 41260373472 |
| 25 | 100196920196 |
| 26 | 241712863504 |
| 27 | 579416535973 |
| 28 | 1380517695672 |
| 29 | 3270075208145 |
| 30 | 7702580246941 |
[1,1,7,25,86,269,862,2606,7812,22704,64989,182356, 504414,1373694,3693367,9804435,25733084,66808578, 171719539,437183839,1103143657,2760037810, 6850400668,16873338215,41260373472,100196920196, 241712863504,579416535973,1380517695672, 3270075208145,7702580246941] |