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 | 40 |
| 3 | 42 |
| 4 | 420 |
| 5 | 4290 |
| 6 | 43890 |
| 7 | 4001970 |
| 8 | 40029990 |
| 9 | 406816410 |
| 10 | 40026056070 |
| 11 | 401120980260 |
| 12 | 40013061952710 |
| 13 | 405332750552730 |
| 14 | 40111962162442170 |
| 15 | 4000228915204892370 |
| 16 | 40909794684132183810 |
| 17 | 4000669166940700163910 |