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 | 10 |
| 3 | 23 |
| 4 | 72 |
| 5 | 335 |
| 6 | 2220 |
| 7 | 19166 |
| 8 | 217862 |
| 9 | 3428059 |
| 10 | 71688050 |
| 11 | 1884401480 |
| 12 | 63363038340 |
| 13 | 2929516409504 |
| 14 | 178211319638172 |
| 15 | 13290584617658383 |
| 16 | 1240111930777216192 |
| 17 | 158642776309162956097 |
| 18 | 26642849845285577276244 |
| 19 | 5432337767302682299726906 |