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 | 21 |
| 3 | 64 |
| 4 | 217 |
| 5 | 671 |
| 6 | 2052 |
| 7 | 6119 |
| 8 | 18001 |
| 9 | 52288 |
| 10 | 150429 |
| 11 | 429243 |
| 12 | 1216516 |
| 13 | 3427659 |
| 14 | 9609357 |
| 15 | 26821696 |
| 16 | 74576737 |
| 17 | 206650199 |
| 18 | 570877956 |
| 19 | 1572754223 |
| 20 | 4322192329 |
| 21 | 11851475008 |
| 22 | 32430381861 |
| 23 | 88576465779 |
| 24 | 241511251972 |
| 25 | 657457204371 |
| 26 | 1787147867397 |
| 27 | 4851349002304 |