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 | 9 |
| 3 | 19 |
| 4 | 57 |
| 5 | 139 |
| 6 | 369 |
| 7 | 963 |
| 8 | 2489 |
| 9 | 6523 |
| 10 | 16929 |
| 11 | 44147 |
| 12 | 114953 |
| 13 | 299307 |
| 14 | 779697 |
| 15 | 2030243 |
| 16 | 5287833 |
| 17 | 13770971 |
| 18 | 35864001 |
| 19 | 93402579 |
| 20 | 243249193 |
| 21 | 633503627 |
| 22 | 1649849553 |
| 23 | 4296752131 |
| 24 | 11190160825 |
| 25 | 29142853947 |
| 26 | 75897603297 |
| 27 | 197662332211 |