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 | 1 |
| 3 | 7 |
| 4 | 37 |
| 5 | 133 |
| 6 | 2431 |
| 7 | 27007 |
| 8 | 176761 |
| 9 | 5329837 |
| 10 | 12994393 |
| 11 | 866792053 |
| 12 | 5213746711 |
| 13 | 841146804577 |
| 14 | 10532583170701 |
| 15 | 569600638022431 |
| 16 | 16539483668991901 |
| 17 | 3333075288160853 |
| 18 | 16955228098102446847 |
| 19 | 932411737877492011 |
| 20 | 10996483739066355827053 |
| 21 | 66024590609554132070857 |