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 | 5 |
| 3 | 25 |
| 4 | 173 |
| 5 | 1297 |
| 6 | 12225 |
| 7 | 124997 |
| 8 | 1492765 |
| 9 | 19452389 |
| 10 | 284145077 |
| 11 | 4500039733 |
| 12 | 78159312233 |
| 13 | 1460072616929 |
| 14 | 29459406350773 |
| 15 | 634783708448137 |
| 16 | 14613962109584749 |
| 17 | 356957383060502945 |
| 18 | 9241222160142506097 |
| 19 | 252390723655315856437 |
| 20 | 7260629936987794508973 |