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 | 1 |
| 2 | -4 |
| 3 | 35 |
| 4 | -455 |
| 5 | 7735 |
| 6 | -161336 |
| 7 | 3973212 |
| 8 | -112587210 |
| 9 | 3603324835 |
| 10 | -128433778935 |
| 11 | 5042279130343 |
| 12 | -216113991649920 |
| 13 | 10038333251577820 |
| 14 | -502213976534135280 |
| 15 | 26920671954736535620 |
| 16 | -1539171664433009622090 |
| 17 | 93492751831594011076131 |
| 18 | -6012423991038631627857900 |