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 | 19 |
| 3 | 82 |
| 4 | 325 |
| 5 | 1216 |
| 6 | 4375 |
| 7 | 15310 |
| 8 | 52489 |
| 9 | 177148 |
| 10 | 590491 |
| 11 | 1948618 |
| 12 | 6377293 |
| 13 | 20726200 |
| 14 | 66961567 |
| 15 | 215233606 |
| 16 | 688747537 |
| 17 | 2195382772 |
| 18 | 6973568803 |
| 19 | 22082967874 |
| 20 | 69735688021 |
| 21 | 219667417264 |
| 22 | 690383311399 |
| 23 | 2165293113022 |
| 24 | 6778308875545 |
| 25 | 21182215236076 |
| 26 | 66088511536555 |
| 27 | 205891132094650 |