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 | 4 |
| 1 | 19 |
| 2 | 91 |
| 3 | 439 |
| 4 | 2119 |
| 5 | 10231 |
| 6 | 49399 |
| 7 | 238519 |
| 8 | 1151671 |
| 9 | 5560759 |
| 10 | 26849719 |
| 11 | 129641911 |
| 12 | 625966519 |
| 13 | 3022433719 |
| 14 | 14593600951 |
| 15 | 70464138679 |
| 16 | 340230958519 |
| 17 | 1642780388791 |
| 18 | 7932045389239 |
| 19 | 38299303112119 |
| 20 | 184925394005431 |
| 21 | 892898788470199 |
| 22 | 4311296729902519 |