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 | 2 |
| 3 | 5 |
| 4 | 15 |
| 5 | 52 |
| 6 | 201 |
| 7 | 843 |
| 8 | 3764 |
| 9 | 17659 |
| 10 | 86245 |
| 11 | 435492 |
| 12 | 2261769 |
| 13 | 12033165 |
| 14 | 65369590 |
| 15 | 361661809 |
| 16 | 2033429427 |
| 17 | 11597912588 |
| 18 | 67004252081 |
| 19 | 391599609911 |
| 20 | 2312726369640 |
| 21 | 13789161819383 |
| 22 | 82932744795049 |
| 23 | 502777950712812 |
| 24 | 3070529443569777 |
| 25 | 18879637374473465 |
| 26 | 116815588935673706 |
| 27 | 727011479685559453 |