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 | 6 |
| 2 | 44 |
| 3 | 352 |
| 4 | 2940 |
| 5 | 25194 |
| 6 | 219604 |
| 7 | 1937520 |
| 8 | 17250012 |
| 9 | 154663960 |
| 10 | 1394538288 |
| 11 | 12631852688 |
| 12 | 114858935204 |
| 13 | 1047772373340 |
| 14 | 9584557428600 |
| 15 | 87885886492320 |
| 16 | 807564936805020 |
| 17 | 7434289153896264 |
| 18 | 68551275793965328 |
| 19 | 633038816547052800 |