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 | 6 |
| 4 | 24 |
| 5 | 119 |
| 6 | 694 |
| 7 | 4580 |
| 8 | 33254 |
| 9 | 260285 |
| 10 | 2163930 |
| 11 | 18900534 |
| 12 | 172016256 |
| 13 | 1621031261 |
| 14 | 15739870457 |
| 15 | 156855197297 |
| 16 | 1599233708733 |
| 17 | 16638560125635 |
| 18 | 176269571712376 |
| 19 | 1898076560618372 |
| 20 | 20742488003444465 |
| 21 | 229747253093647567 |
| 22 | 2576270755655436479 |
| 23 | 29218474225923168362 |