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 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 1 |
| 5 | 25 |
| 6 | 145 |
| 7 | 505 |
| 8 | 1345 |
| 9 | 3025 |
| 10 | 78625 |
| 11 | 809425 |
| 12 | 4809025 |
| 13 | 20787625 |
| 14 | 72696625 |
| 15 | 1961583625 |
| 16 | 28478346625 |
| 17 | 238536558625 |
| 18 | 1425925698625 |
| 19 | 6764765838625 |
| 20 | 189239120970625 |
| 21 | 3500701266525625 |
| 22 | 37764092547420625 |
| 23 | 288099608198025625 |