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 | 3 |
| 1 | 21 |
| 2 | 231 |
| 3 | 1155 |
| 4 | 21945 |
| 5 | 504735 |
| 6 | 4542615 |
| 7 | 140821065 |
| 8 | 140821065 |
| 9 | 1830673845 |
| 10 | 78718975335 |
| 11 | 3699791840745 |
| 12 | 62896461292665 |
| 13 | 62896461292665 |
| 14 | 3710891216267235 |
| 15 | 3710891216267235 |
| 16 | 248629711489904745 |