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) |
|---|---|
| 2 | 1 |
| 3 | 1 |
| 4 | 7 |
| 5 | 21 |
| 6 | 66 |
| 7 | 143 |
| 8 | 715 |
| 9 | 2431 |
| 10 | 8398 |
| 11 | 29393 |
| 12 | 104006 |
| 13 | 371450 |
| 14 | 1337220 |
| 15 | 3231615 |
| 16 | 17678835 |
| 17 | 64822395 |
| 18 | 238819350 |
| 19 | 883631595 |
| 20 | 3282060210 |
| 21 | 12233133510 |
| 22 | 45741281820 |
| 23 | 171529806825 |
| 24 | 644952073662 |
| 25 | 2430973200726 |
| 26 | 9183676536076 |
| 27 | 34766775458002 |
| 28 | 131873975875180 |