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 | 1 |
| 3 | -3 |
| 4 | 11 |
| 5 | -49 |
| 6 | 259 |
| 7 | -1589 |
| 8 | 11109 |
| 9 | -87171 |
| 10 | 758121 |
| 11 | -7229859 |
| 12 | 74905467 |
| 13 | -836159961 |
| 14 | 9980000667 |
| 15 | -126422745813 |
| 16 | 1686902233653 |
| 17 | -23512989735963 |
| 18 | 338917341235473 |
| 19 | -4982536435536387 |
| 20 | 73087736506615467 |
| 21 | -1025163078325255233 |
| 22 | 12286912220375608179 |