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 | 26 |
| 3 | 129 |
| 4 | 546 |
| 5 | 2010 |
| 6 | 6615 |
| 7 | 19650 |
| 8 | 53790 |
| 9 | 137035 |
| 10 | 328262 |
| 11 | 745078 |
| 12 | 1613072 |
| 13 | 3348198 |
| 14 | 6693822 |
| 15 | 12937656 |
| 16 | 24253200 |
| 17 | 44219610 |
| 18 | 78604130 |
| 19 | 136511100 |
| 20 | 232054284 |