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 | 0 |
| 3 | 2 |
| 4 | 3 |
| 5 | 6 |
| 6 | 20 |
| 7 | 65 |
| 8 | 134 |
| 9 | 482 |
| 10 | 1562 |
| 11 | 4974 |
| 12 | 15466 |
| 13 | 51768 |
| 14 | 179055 |
| 15 | 631737 |
| 16 | 2216757 |
| 17 | 7905325 |
| 18 | 28768472 |
| 19 | 106852116 |
| 20 | 402255207 |
| 21 | 1532029660 |
| 22 | 5902839974 |
| 23 | 23041880550 |
| 24 | 91129833143 |
| 25 | 364957188701 |
| 26 | 1478719359501 |
| 27 | 6058859894440 |
| 28 | 25100003070184 |
| 29 | 105123020009481 |
| 30 | 445036528737301 |