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 | 0 |
| 1 | 1 |
| 2 | 6 |
| 3 | 25 |
| 4 | 90 |
| 5 | 306 |
| 6 | 1004 |
| 7 | 3226 |
| 8 | 10218 |
| 9 | 32043 |
| 10 | 99748 |
| 11 | 308787 |
| 12 | 951772 |
| 13 | 2923563 |
| 14 | 8955342 |
| 15 | 27368895 |
| 16 | 83484042 |
| 17 | 254244033 |
| 18 | 773219196 |
| 19 | 2348780937 |
| 20 | 7127522136 |
| 21 | 21609615822 |
| 22 | 65465845254 |
| 23 | 198189732798 |
| 24 | 599624708588 |
| 25 | 1813169256151 |
| 26 | 5480019176754 |
| 27 | 16555101318735 |