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 | 3 |
| 1 | 8 |
| 2 | 21 |
| 3 | 55 |
| 4 | 145 |
| 5 | 381 |
| 6 | 1001 |
| 7 | 2633 |
| 8 | 6921 |
| 9 | 18193 |
| 10 | 47833 |
| 11 | 125745 |
| 12 | 330569 |
| 13 | 869057 |
| 14 | 2284665 |
| 15 | 6006193 |
| 16 | 15789865 |
| 17 | 41510241 |
| 18 | 109127129 |
| 19 | 286886801 |