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) |
|---|---|
| 4 | 1 |
| 5 | 5 |
| 6 | 25 |
| 7 | 105 |
| 8 | 441 |
| 9 | 1785 |
| 10 | 7308 |
| 11 | 29898 |
| 12 | 124641 |
| 13 | 526669 |
| 14 | 2276846 |
| 15 | 10038964 |
| 16 | 45353269 |
| 17 | 209442533 |
| 18 | 990777442 |
| 19 | 4791502156 |
| 20 | 23707812077 |
| 21 | 119810145337 |
| 22 | 618483875689 |
| 23 | 3256714122209 |
| 24 | 17488997849803 |
| 25 | 95671400358075 |
| 26 | 532959538382100 |
| 27 | 3020603738202750 |
| 28 | 17411069344112895 |