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 | -1023 |
| 3 | -59048 |
| 4 | -1048575 |
| 5 | -9765624 |
| 6 | -60466175 |
| 7 | -282475248 |
| 8 | -1073741823 |
| 9 | -3486784400 |
| 10 | -9999999999 |
| 11 | -25937424600 |
| 12 | -61917364223 |
| 13 | -137858491848 |
| 14 | -289254654975 |
| 15 | -576650390624 |
| 16 | -1099511627775 |
| 17 | -2015993900448 |