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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 4 |
| 2 | 16 |
| 3 | 64 |
| 4 | 257 |
| 5 | 1028 |
| 6 | 4112 |
| 7 | 16448 |
| 8 | 65793 |
| 9 | 263172 |
| 10 | 1052688 |
| 11 | 4210752 |
| 12 | 16843009 |
| 13 | 67372036 |
| 14 | 269488144 |
| 15 | 1077952576 |
| 16 | 4311810305 |
| 17 | 17247241220 |
| 18 | 68988964880 |
| 19 | 275955859520 |
| 20 | 1103823438081 |
| 21 | 4415293752324 |
| 22 | 17661175009296 |
| 23 | 70644700037184 |
[1,4,16,64,257,1028,4112,16448,65793,263172, 1052688,4210752,16843009,67372036,269488144, 1077952576,4311810305,17247241220,68988964880, 275955859520,1103823438081,4415293752324, 17661175009296,70644700037184] |