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 | 2 |
| 2 | 14 |
| 3 | 98 |
| 4 | 726 |
| 5 | 5522 |
| 6 | 42770 |
| 7 | 335512 |
| 8 | 2656998 |
| 9 | 21195944 |
| 10 | 170076214 |
| 11 | 1371181110 |
| 12 | 11098310730 |
| 13 | 90128497032 |
| 14 | 734008622872 |
| 15 | 5992486341248 |
| 16 | 49028047353670 |
| 17 | 401885885751630 |
| 18 | 3299812135410080 |
| 19 | 27134786911366212 |
| 20 | 223433635272820126 |
| 21 | 1842041118321640390 |