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 | 21 |
| 2 | 441 |
| 3 | 1889 |
| 4 | 8465 |
| 5 | 50139 |
| 6 | 220882 |
| 7 | 891720 |
| 8 | 3919354 |
| 9 | 16153614 |
| 10 | 62844340 |
| 11 | 248939744 |
| 12 | 971561382 |
| 13 | 3682206767 |
| 14 | 13939172767 |
| 15 | 52509796817 |
| 16 | 195002378289 |
| 17 | 720554922955 |
| 18 | 2654209247431 |
| 19 | 9705662821905 |
| 20 | 35326530765908 |
| 21 | 128233462946586 |