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 | 39 |
| 4 | 177 |
| 5 | 783 |
| 6 | 3369 |
| 7 | 14199 |
| 8 | 58977 |
| 9 | 242463 |
| 10 | 989529 |
| 11 | 4017159 |
| 12 | 16245777 |
| 13 | 65514543 |
| 14 | 263652489 |
| 15 | 1059392919 |
| 16 | 4251920577 |
| 17 | 17050729023 |
| 18 | 68332056249 |
| 19 | 273715645479 |
| 20 | 1096024843377 |
| 21 | 4387586157903 |
| 22 | 17560804984809 |
| 23 | 70274600998839 |
| 24 | 281192547174177 |
| 25 | 1125052618233183 |