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 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 2 |
| 5 | 15 |
| 6 | 110 |
| 7 | 936 |
| 8 | 12073 |
| 9 | 273972 |
| 10 | 12003332 |
| 11 | 1018992968 |
| 12 | 165091159269 |
| 13 | 50502031331411 |
| 14 | 29054155657134165 |
| 15 | 31426485969804026075 |
| 16 | 64001015704527557101231 |
| 17 | 245935864153532932681481794 |
| 18 | 1787577725145611700547871854870 |
| 19 | 24637809253125004524383007473440146 |