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) |
|---|---|
| 0 | 1 |
| 1 | 40 |
| 2 | 900 |
| 3 | 15000 |
| 4 | 206250 |
| 5 | 2475000 |
| 6 | 26812500 |
| 7 | 268125000 |
| 8 | 2513671875 |
| 9 | 22343750000 |
| 10 | 189921875000 |
| 11 | 1553906250000 |
| 12 | 12301757812500 |
| 13 | 94628906250000 |
| 14 | 709716796875000 |
| 15 | 5204589843750000 |
| 16 | 37407989501953125 |
| 17 | 264056396484375000 |
| 18 | 1833724975585937500 |
| 19 | 12546539306640625000 |