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 | 10 |
| 3 | 57 |
| 4 | 292 |
| 5 | 1585 |
| 6 | 9726 |
| 7 | 68425 |
| 8 | 547912 |
| 9 | 4931937 |
| 10 | 49320370 |
| 11 | 542525401 |
| 12 | 6510306540 |
| 13 | 84633987217 |
| 14 | 1184875823782 |
| 15 | 17773137360105 |
| 16 | 284370197765776 |
| 17 | 4834293362023105 |
| 18 | 87017280516421722 |
| 19 | 1653328329812019577 |
| 20 | 33066566596240399540 |
| 21 | 694397898521048399601 |