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 | 2 |
| 3 | 20 |
| 4 | 298 |
| 5 | 5492 |
| 6 | 116124 |
| 7 | 2710776 |
| 8 | 68308170 |
| 9 | 1831522940 |
| 10 | 51744512380 |
| 11 | 1529687560328 |
| 12 | 47075470016012 |
| 13 | 1502258036769256 |
| 14 | 49560341916549320 |
| 15 | 1686236991420431760 |
| 16 | 59054595629732284890 |
| 17 | 2125432920387784135812 |
| 18 | 78509698415432235272292 |
| 19 | 2972996232264052816975752 |
| 20 | 115303660044380692013332428 |