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 | 4 |
| 2 | 30 |
| 3 | 246 |
| 4 | 2037 |
| 5 | 16886 |
| 6 | 139997 |
| 7 | 1160693 |
| 8 | 9623140 |
| 9 | 79784098 |
| 10 | 661478734 |
| 11 | 5484227157 |
| 12 | 45468956106 |
| 13 | 376976720745 |
| 14 | 3125460977225 |
| 15 | 25912757426660 |
| 16 | 214839027697334 |
| 17 | 1781200165693270 |
| 18 | 14767680082482085 |
| 19 | 122436758775876478 |