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 | 9 |
| 4 | 43 |
| 5 | 165 |
| 6 | 571 |
| 7 | 1869 |
| 8 | 5923 |
| 9 | 18405 |
| 10 | 56491 |
| 11 | 172029 |
| 12 | 521203 |
| 13 | 1573845 |
| 14 | 4742011 |
| 15 | 14266989 |
| 16 | 42882883 |
| 17 | 128812485 |
| 18 | 386765131 |
| 19 | 1160950749 |
| 20 | 3484162963 |
| 21 | 10455110325 |
| 22 | 31370573851 |
| 23 | 94122207309 |
| 24 | 282387593443 |
| 25 | 847204723365 |
| 26 | 2541698056171 |
| 27 | 7625261940669 |