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) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 9 |
| 5 | 21 |
| 6 | 56 |
| 7 | 164 |
| 8 | 557 |
| 9 | 2223 |
| 10 | 10766 |
| 11 | 64956 |
| 12 | 501696 |
| 13 | 5067146 |
| 14 | 67997750 |
| 15 | 1224275498 |
| 16 | 29733449510 |
| 17 | 976520265678 |
| 18 | 43425320764422 |
| 19 | 2616632636247976 |
| 20 | 213796933371366930 |
| 21 | 23704270652844196754 |
| 22 | 3569464106212250952762 |
| 23 | 730647291666881838671052 |