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 | 3 |
| 2 | 21 |
| 3 | 903 |
| 4 | 1631721 |
| 5 | 5325028475403 |
| 6 | 56711856527710922180500221 |
| 7 | 82753323662259982099234097722219590008756576353188748920925694383267934319786203404455994065868822592721 |