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 | 4 |
| 3 | 25 |
| 4 | 197 |
| 5 | 1797 |
| 6 | 18178 |
| 7 | 198937 |
| 8 | 2318858 |
| 9 | 28487593 |
| 10 | 366129764 |
| 11 | 4896068759 |
| 12 | 67843403960 |
| 13 | 971032668429 |
| 14 | 14319735032679 |
| 15 | 217136949146091 |
| 16 | 3379973833321141 |
| 17 | 53936100582832901 |
| 18 | 881318215466710693 |
| 19 | 14731508761600217914 |