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) |
|---|---|
| 1 | 4 |
| 2 | 152 |
| 3 | 2630 |
| 4 | 31500 |
| 5 | 303534 |
| 6 | 2530976 |
| 7 | 19030428 |
| 8 | 132386340 |
| 9 | 866782510 |
| 10 | 5405853200 |