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 | 4 |
| 2 | 17 |
| 3 | 80 |
| 4 | 401 |
| 5 | 2084 |
| 6 | 11073 |
| 7 | 59712 |
| 8 | 325441 |
| 9 | 1788004 |
| 10 | 9885457 |
| 11 | 54932176 |
| 12 | 306528145 |
| 13 | 1716461764 |
| 14 | 9640310017 |
| 15 | 54282691840 |
| 16 | 306337928449 |
| 17 | 1732172652868 |
| 18 | 9811489710737 |
| 19 | 55660919625680 |
| 20 | 316204733423121 |
| 21 | 1798580947651044 |