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 | 3 |
| 3 | 15 |
| 4 | 82 |
| 5 | 485 |
| 6 | 3039 |
| 7 | 19862 |
| 8 | 133969 |
| 9 | 925805 |
| 10 | 6521690 |
| 11 | 46658955 |
| 12 | 338115321 |
| 13 | 2476585674 |
| 14 | 18306446887 |
| 15 | 136384608971 |
| 16 | 1023041170426 |
| 17 | 7720127405881 |
| 18 | 58567844563843 |
| 19 | 446422706023630 |
| 20 | 3417223098702669 |
| 21 | 26257867836211825 |