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 | 3 |
| 3 | 4 |
| 4 | 3 |
| 5 | -15 |
| 6 | -118 |
| 7 | -336 |
| 8 | -595 |
| 9 | 1467 |
| 10 | 20391 |
| 11 | 96205 |
| 12 | 353686 |
| 13 | 574786 |
| 14 | -2717256 |
| 15 | -30598208 |
| 16 | -197828371 |
| 17 | -841728699 |
| 18 | -2599029153 |
| 19 | -1309899955 |
| 20 | 56975269295 |
| 21 | 522707807733 |
| 22 | 3425068059553 |
| 23 | 16747743739845 |
| 24 | 63468629516172 |
| 25 | 111911654532374 |
| 26 | -907903172853988 |
| 27 | -12555837715110897 |