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 | 2 |
| 2 | 4 |
| 3 | 21 |
| 4 | 130 |
| 5 | 1135 |
| 6 | 12448 |
| 7 | 154441 |
| 8 | 2283922 |
| 9 | 38761556 |
| 10 | 721082359 |
| 11 | 14999247901 |
| 12 | 345288253975 |
| 13 | 8513996163751 |
| 14 | 228807509644648 |
| 15 | 6634125686206751 |
| 16 | 203954623297226722 |
| 17 | 6705169274925371251 |
| 18 | 234777003656354137054 |
| 19 | 8632415297513570062501 |
| 20 | 335879068944350793715480 |