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 | 4 |
| 3 | 28 |
| 4 | 317 |
| 5 | 4606 |
| 6 | 84477 |
| 7 | 1919575 |
| 8 | 47891482 |
| 9 | 1512466345 |
| 10 | 48627032377 |
| 11 | 1930020260416 |
| 12 | 77986967769593 |
| 13 | 3624337209819538 |
| 14 | 178110510699972510 |
| 15 | 9381158756438306167 |
| 16 | 548676565488760277878 |
| 17 | 31900481466759651567625 |
| 18 | 2189463436999785648552851 |
| 19 | 144075114432622269076465962 |