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 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 21 |
| 5 | 193 |
| 6 | 2125 |
| 7 | 32281 |
| 8 | 655235 |
| 9 | 15530705 |
| 10 | 427214889 |
| 11 | 14127457681 |
| 12 | 542796582295 |
| 13 | 23400843532969 |
| 14 | 1140401734145453 |
| 15 | 62743287535847465 |
| 16 | 3822548966261363595 |
| 17 | 256275705820386124321 |
| 18 | 18923726002188870476497 |