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) |
|---|---|
| 1 | 0 |
| 2 | 1 |
| 3 | 5 |
| 4 | 25 |
| 5 | 130 |
| 6 | 951 |
| 7 | 9552 |
| 8 | 160220 |
| 9 | 4756703 |
| 10 | 264964172 |
| 11 | 27746801125 |
| 12 | 5419696866001 |
| 13 | 1964101824992259 |
| 14 | 1319988856541150115 |
| 15 | 1648566523004692022634 |
| 16 | 3838409698542815296758222 |
| 17 | 16719797018733808721401666187 |
| 18 | 136732968429033400292302529059213 |