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 | 25 |
| 5 | 121 |
| 6 | 361 |
| 7 | 3361 |
| 8 | 42001 |
| 9 | 275185 |
| 10 | 1819441 |
| 11 | 30777121 |
| 12 | 371238121 |
| 13 | 3057311401 |
| 14 | 44263763545 |
| 15 | 801096528961 |
| 16 | 9710981323681 |
| 17 | 125367419194081 |
| 18 | 2643123767954401 |
| 19 | 45840730383002305 |
| 20 | 646414025466298681 |
| 21 | 13258301279836276441 |