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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 7 |
| 4 | 31 |
| 5 | 69 |
| 6 | 307 |
| 7 | 683 |
| 8 | 3039 |
| 9 | 18917 |
| 10 | 40873 |
| 11 | 264155 |
| 12 | 1097493 |
| 13 | 2459141 |
| 14 | 10934057 |
| 15 | 68063483 |
| 16 | 419314955 |
| 17 | 906693393 |
| 18 | 5859475313 |
| 19 | 24344594645 |
| 20 | 54548664603 |
| 21 | 351636582263 |
| 22 | 1461094993655 |
| 23 | 9118206544193 |
[1,1,3,7,31,69,307,683,3039,18917,40873,264155, 1097493,2459141,10934057,68063483,419314955, 906693393,5859475313,24344594645,54548664603, 351636582263,1461094993655,9118206544193] |