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 | 2 |
| 2 | 6 |
| 3 | 66 |
| 4 | 858 |
| 5 | 6006 |
| 6 | 222222 |
| 7 | 20522502 |
| 8 | 244868442 |
| 9 | 6172882716 |
| 10 | 231645546132 |
| 11 | 49795711759794 |
| 12 | 2415957997595142 |
| 13 | 495677121121776594 |
| 14 | 22181673755737618122 |
| 15 | 5521159517777159511255 |
| 16 | 477552751050050157255774 |
| 17 | 200345274602020206472543002 |