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 | 1 |
| 1 | 4 |
| 2 | 28 |
| 3 | 232 |
| 4 | 2108 |
| 5 | 20384 |
| 6 | 206392 |
| 7 | 2165720 |
| 8 | 23385340 |
| 9 | 258532216 |
| 10 | 2915343808 |
| 11 | 33437862352 |
| 12 | 389230520888 |
| 13 | 4590271681064 |
| 14 | 54767161155000 |
| 15 | 660307913374352 |
| 16 | 8036973478493436 |
| 17 | 98672644594401736 |
| 18 | 1221090110502080440 |
| 19 | 15222093531642444504 |