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 | 20 |
| 3 | 84 |
| 4 | 276 |
| 5 | 1108 |
| 6 | 5396 |
| 7 | 20564 |
| 8 | 65812 |
| 9 | 263252 |
| 10 | 1316116 |
| 11 | 5525588 |
| 12 | 18153748 |
| 13 | 72352852 |
| 14 | 352326932 |
| 15 | 1342197844 |
| 16 | 4295033108 |
| 17 | 17180132436 |
| 18 | 85900662036 |
| 19 | 360782778452 |
| 20 | 1185429127444 |
| 21 | 4758896116820 |
| 22 | 23175995856148 |
| 23 | 88323049672788 |