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) |
|---|---|
| 3 | 1 |
| 4 | 3 |
| 5 | 9 |
| 6 | 31 |
| 7 | 102 |
| 8 | 328 |
| 9 | 1035 |
| 10 | 3217 |
| 11 | 9880 |
| 12 | 30062 |
| 13 | 90803 |
| 14 | 272697 |
| 15 | 815228 |
| 16 | 2428298 |
| 17 | 7212179 |
| 18 | 21370921 |
| 19 | 63207913 |
| 20 | 186668355 |
| 21 | 550617011 |
| 22 | 1622604097 |
| 23 | 4777983482 |
| 24 | 14060981252 |
| 25 | 41360234037 |
| 26 | 121616984851 |
| 27 | 357510486913 |
| 28 | 1050750138523 |