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 | 5 |
| 3 | 15 |
| 4 | 55 |
| 5 | 170 |
| 6 | 571 |
| 7 | 1789 |
| 8 | 5727 |
| 9 | 17836 |
| 10 | 55627 |
| 11 | 171169 |
| 12 | 524879 |
| 13 | 1595896 |
| 14 | 4829894 |
| 15 | 14527981 |
| 16 | 43497312 |
| 17 | 129588391 |
| 18 | 384430264 |
| 19 | 1135607519 |
| 20 | 3341662498 |
| 21 | 9796626673 |
| 22 | 28620419254 |
| 23 | 83334382425 |
| 24 | 241879403752 |
| 25 | 699937499318 |
| 26 | 2019607806247 |
| 27 | 5811320364410 |
| 28 | 16677611788799 |