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 | 6 |
| 4 | 39 |
| 5 | 273 |
| 6 | 2013 |
| 7 | 15330 |
| 8 | 119572 |
| 9 | 949560 |
| 10 | 7646457 |
| 11 | 62263994 |
| 12 | 511647711 |
| 13 | 4236443046 |
| 14 | 35303691969 |
| 15 | 295820592090 |
| 16 | 2490618533403 |
| 17 | 21057047599918 |
| 18 | 178684089639276 |
| 19 | 1521229411793910 |
| 20 | 12988958823773660 |
| 21 | 111198159686496300 |
| 22 | 954235370332956621 |
| 23 | 8206424184863387028 |