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 | 4578 |
| 8 | 33184 |
| 9 | 258757 |
| 10 | 2136978 |
| 11 | 18478134 |
| 12 | 165857600 |
| 13 | 1535336290 |
| 14 | 14584260700 |
| 15 | 141603589300 |
| 16 | 1400942032152 |
| 17 | 14087464765300 |
| 18 | 143689133196008 |
| 19 | 1484090443264936 |
| 20 | 15499968503875136 |
| 21 | 163501005435759505 |
| 22 | 1740170514634463426 |
| 23 | 18671118911254798454 |