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 | 3 |
| 3 | 17 |
| 4 | 137 |
| 5 | 1389 |
| 6 | 16819 |
| 7 | 236557 |
| 8 | 3792753 |
| 9 | 68326073 |
| 10 | 1366917731 |
| 11 | 30074632521 |
| 12 | 721798881913 |
| 13 | 18766625660197 |
| 14 | 525460685327187 |
| 15 | 15763716503597189 |
| 16 | 504436925448024929 |
| 17 | 17150818356045629937 |
| 18 | 617428780939911647683 |
| 19 | 23462281235407345160833 |