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 | 12 |
| 3 | 35 |
| 4 | 101 |
| 5 | 291 |
| 6 | 839 |
| 7 | 2423 |
| 8 | 7011 |
| 9 | 20326 |
| 10 | 59038 |
| 11 | 171777 |
| 12 | 500603 |
| 13 | 1461032 |
| 14 | 4269828 |
| 15 | 12493857 |
| 16 | 36599403 |
| 17 | 107325540 |
| 18 | 315027276 |
| 19 | 925501857 |
| 20 | 2721208599 |
| 21 | 8007114171 |
| 22 | 23577440439 |
| 23 | 69470880381 |
| 24 | 204821487269 |
| 25 | 604223501426 |
| 26 | 1783419354954 |
| 27 | 5266582196407 |
| 28 | 15560042628205 |