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 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 7 |
| 4 | 31 |
| 5 | 191 |
| 6 | 1331 |
| 7 | 10655 |
| 8 | 95887 |
| 9 | 958879 |
| 10 | 10547659 |
| 11 | 126571919 |
| 12 | 1645434935 |
| 13 | 23036089103 |
| 14 | 345541336531 |
| 15 | 5528661384511 |
| 16 | 93987243536671 |
| 17 | 1691770383660095 |
| 18 | 32143637289541787 |
| 19 | 642872745790835759 |
| 20 | 13500327661607550919 |