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 | 216 |
| 5 | 38070 |
| 6 | 1314600 |
| 7 | 21191208 |
| 8 | 207830308 |
| 9 | 1442794332 |
| 10 | 7775083960 |
| 11 | 34530764200 |
| 12 | 131660992164 |
| 13 | 443702617356 |
| 14 | 1350258600008 |
| 15 | 3771242866680 |
| 16 | 9789675562020 |
| 17 | 23856321869260 |
| 18 | 55015308882264 |
| 19 | 120855465245464 |
| 20 | 254284702668580 |
| 21 | 514791197224860 |
| 22 | 1006655249550696 |