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 | 1 |
| 2 | 1 |
| 3 | 0 |
| 4 | 4 |
| 5 | 9 |
| 6 | 25 |
| 7 | 76 |
| 8 | 216 |
| 9 | 625 |
| 10 | 1809 |
| 11 | 5224 |
| 12 | 15100 |
| 13 | 43641 |
| 14 | 126121 |
| 15 | 364500 |
| 16 | 1053424 |
| 17 | 3044449 |
| 18 | 8798625 |
| 19 | 25428496 |
| 20 | 73489716 |
| 21 | 212389225 |
| 22 | 613816249 |
| 23 | 1773961884 |
| 24 | 5126845000 |
| 25 | 14816857041 |
| 26 | 42821511601 |
| 27 | 123756465400 |
| 28 | 357662823084 |
| 29 | 1033664743129 |
| 30 | 2987346551625 |