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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 7 |
| 3 | 28 |
| 4 | 112 |
| 5 | 196 |
| 6 | 703 |
| 7 | 2812 |
| 8 | 4921 |
| 9 | 19684 |
| 10 | 78736 |
| 11 | 137788 |
| 12 | 551152 |
| 13 | 2204608 |
| 14 | 3858064 |
| 15 | 13837852 |
| 16 | 55351408 |
| 17 | 96864964 |
| 18 | 387400807 |
| 19 | 1549603228 |
| 20 | 2711805649 |
| 21 | 10847222596 |
| 22 | 43388890384 |
| 23 | 75930558172 |
| 24 | 272342767321 |
| 25 | 1089371069284 |
[1,4,7,28,112,196,703,2812,4921,19684,78736, 137788,551152,2204608,3858064,13837852,55351408, 96864964,387400807,1549603228,2711805649, 10847222596,43388890384,75930558172,272342767321, 1089371069284] |