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 | 1 |
| 2 | 3 |
| 3 | 10 |
| 4 | 47 |
| 5 | 276 |
| 6 | 2022 |
| 7 | 17606 |
| 8 | 179391 |
| 9 | 2093860 |
| 10 | 27581888 |
| 11 | 404680398 |
| 12 | 6541528886 |
| 13 | 115437202986 |
| 14 | 2206844818622 |
| 15 | 45408726154590 |
| 16 | 1000134868827263 |
| 17 | 23468606700087972 |
| 18 | 584340284516996400 |
| 19 | 15383829737201853518 |
| 20 | 426915367401366308112 |
| 21 | 12454073547413511363878 |