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 | 1 |
| 2 | 4 |
| 3 | 16 |
| 4 | 78 |
| 5 | 404 |
| 6 | 2208 |
| 7 | 12492 |
| 8 | 72589 |
| 9 | 430569 |
| 10 | 2596471 |
| 11 | 15870357 |
| 12 | 98102191 |
| 13 | 612222083 |
| 14 | 3852015239 |
| 15 | 24408653703 |
| 16 | 155629858911 |
| 17 | 997744376239 |
| 18 | 6427757480074 |
| 19 | 41590254520410 |
| 20 | 270163621543421 |
| 21 | 1761179219680657 |