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 | 15 |
| 2 | 69 |
| 3 | 255 |
| 4 | 1097 |
| 5 | 4765 |
| 6 | 21237 |
| 7 | 95873 |
| 8 | 437537 |
| 9 | 2012997 |
| 10 | 9321899 |
| 11 | 43397633 |
| 12 | 202926209 |
| 13 | 952396005 |
| 14 | 4484003747 |
| 15 | 21168581905 |
| 16 | 100170213121 |
| 17 | 474981809053 |
| 18 | 2256307682541 |
| 19 | 10735210220803 |
| 20 | 51148724456627 |
| 21 | 244007372314919 |