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 | 3 |
| 2 | 21 |
| 3 | 252 |
| 4 | 4369 |
| 5 | 103158 |
| 6 | 3037530 |
| 7 | 106237176 |
| 8 | 4311810305 |
| 9 | 198756808749 |
| 10 | 10250010815226 |
| 11 | 584603613083988 |
| 12 | 36529334450076658 |
| 13 | 2481455748310337022 |
| 14 | 182070232515259616850 |
| 15 | 14349345894391097803752 |