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 | 4 |
| 2 | 21 |
| 3 | 220 |
| 4 | 5985 |
| 5 | 501942 |
| 6 | 143218999 |
| 7 | 145944307080 |
| 8 | 542150225230185 |
| 9 | 7398714129087308170 |
| 10 | 372134605932348010322571 |
| 11 | 69146263065062394421802892300 |
| 12 | 47589861944854471977019273909187085 |