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 | 3 |
| 2 | 20 |
| 3 | 136 |
| 4 | 928 |
| 5 | 6336 |
| 6 | 43264 |
| 7 | 295424 |
| 8 | 2017280 |
| 9 | 13774848 |
| 10 | 94060544 |
| 11 | 642285568 |
| 12 | 4385800192 |
| 13 | 29948116992 |
| 14 | 204498534400 |
| 15 | 1396403339264 |
| 16 | 9535238438912 |
| 17 | 65110680797184 |
| 18 | 444603538866176 |
| 19 | 3035942864551936 |
| 20 | 20730714605486080 |