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 | 0 |
| 2 | 10668 |
| 3 | 317952 |
| 4 | 3747430 |
| 5 | 24569856 |
| 6 | 117503960 |
| 7 | 428990464 |
| 8 | 1355705388 |
| 9 | 3631734784 |
| 10 | 9033649880 |
| 11 | 19996626432 |
| 12 | 42549627976 |
| 13 | 82713667584 |
| 14 | 157758704304 |
| 15 | 279165280256 |
| 16 | 490745951846 |
| 17 | 808950325248 |
| 18 | 1335670719108 |
| 19 | 2081937198592 |
| 20 | 3270650346456 |
| 21 | 4874720530432 |