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 | 0 |
| 1 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 7 |
| 5 | 20 |
| 6 | 66 |
| 7 | 212 |
| 8 | 715 |
| 9 | 2424 |
| 10 | 8398 |
| 11 | 29372 |
| 12 | 104006 |
| 13 | 371384 |
| 14 | 1337220 |
| 15 | 4847208 |
| 16 | 17678835 |
| 17 | 64821680 |
| 18 | 238819350 |
| 19 | 883629164 |
| 20 | 3282060210 |
| 21 | 12233125112 |
| 22 | 45741281820 |
| 23 | 171529777432 |
| 24 | 644952073662 |
| 25 | 2430973096720 |
| 26 | 9183676536076 |