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 | 0 |
| 3 | 0 |
| 4 | 1 |
| 5 | 11 |
| 6 | 80 |
| 7 | 503 |
| 8 | 2993 |
| 9 | 17609 |
| 10 | 105017 |
| 11 | 644528 |
| 12 | 4107600 |
| 13 | 27313805 |
| 14 | 189866541 |
| 15 | 1379728831 |
| 16 | 10470032837 |
| 17 | 82833202559 |
| 18 | 681977545967 |
| 19 | 5832430910181 |
| 20 | 51723181525978 |
| 21 | 474866750479993 |
| 22 | 4506706112772881 |
| 23 | 44151975623559477 |
| 24 | 445958774322599940 |
| 25 | 4638590033810841345 |