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 | 5 |
| 2 | 40 |
| 3 | 285 |
| 4 | 2020 |
| 5 | 13876 |
| 6 | 93885 |
| 7 | 624480 |
| 8 | 4100470 |
| 9 | 26609290 |
| 10 | 170940381 |
| 11 | 1088260190 |
| 12 | 6872684570 |
| 13 | 43088845030 |
| 14 | 268374618310 |
| 15 | 1661512492031 |
| 16 | 10229763359245 |
| 17 | 62663268647185 |
| 18 | 382039881168240 |
| 19 | 2318974249801205 |
| 20 | 14018511922088296 |
| 21 | 84418983571948025 |