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 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 25 |
| 5 | 1895 |
| 6 | 70370 |
| 7 | 1868650 |
| 8 | 41062035 |
| 9 | 802349205 |
| 10 | 14514339340 |
| 11 | 249104207000 |
| 12 | 4120588431245 |
| 13 | 66392465654515 |
| 14 | 1049608974433110 |
| 15 | 16365222591176550 |
| 16 | 252584307401055655 |
| 17 | 3869412829938587825 |
| 18 | 58950765174112191680 |
| 19 | 894469325684769169300 |
| 20 | 13531152125348360663265 |