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 | -1 |
| 2 | 4 |
| 3 | -3 |
| 4 | 20 |
| 5 | 2 |
| 6 | 128 |
| 7 | 173 |
| 8 | 1084 |
| 9 | 2694 |
| 10 | 11408 |
| 11 | 35970 |
| 12 | 136072 |
| 13 | 470756 |
| 14 | 1732928 |
| 15 | 6228989 |
| 16 | 22899692 |
| 17 | 83845406 |
| 18 | 309947888 |
| 19 | 1147367414 |
| 20 | 4269385592 |
| 21 | 15927495836 |
| 22 | 59627571968 |
| 23 | 223804469714 |
| 24 | 842295207896 |
| 25 | 3177355985660 |
| 26 | 12012641100832 |