This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 24 |
| 3 | 228 |
| 4 | 2256 |
| 5 | 22512 |
| 6 | 225024 |
| 7 | 2250048 |
| 8 | 22500096 |
| 9 | 225000192 |
| 10 | 2250000384 |
| 11 | 22500000768 |
| 12 | 225000001536 |
| 13 | 2250000003072 |
| 14 | 22500000006144 |
| 15 | 225000000012288 |
| 16 | 2250000000024576 |
| 17 | 22500000000049152 |
| 18 | 225000000000098304 |
| 19 | 2250000000000196608 |
| 20 | 22500000000000393216 |