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 | 64 |
| 2 | 665 |
| 3 | 2037 |
| 4 | -1316 |
| 5 | -1148 |
| 6 | 16400 |
| 7 | -116032 |
| 8 | 809592 |
| 9 | -6059424 |
| 10 | 49512792 |
| 11 | -442266888 |
| 12 | 4302605280 |
| 13 | -45351578400 |
| 14 | 515054655360 |
| 15 | -6268075470720 |
| 16 | 81309027784320 |
| 17 | -1118525784929280 |
| 18 | 16235659302272640 |
| 19 | -247395991797912960 |
| 20 | 3936073920965890560 |
| 21 | -64988868076072657920 |