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 | 1 |
| 3 | -4 |
| 4 | 4 |
| 5 | -9 |
| 6 | 15 |
| 7 | -22 |
| 8 | 37 |
| 9 | -56 |
| 10 | 92 |
| 11 | -133 |
| 12 | 210 |
| 13 | -310 |
| 14 | 466 |
| 15 | -696 |
| 16 | 1013 |
| 17 | -1495 |
| 18 | 2160 |
| 19 | -3141 |
| 20 | 4495 |
| 21 | -6462 |
| 22 | 9172 |
| 23 | -13024 |
| 24 | 18387 |
| 25 | -25840 |
| 26 | 36213 |
| 27 | -50500 |
| 28 | 70280 |
| 29 | -97302 |
| 30 | 134522 |
| 31 | -185105 |
| 32 | 254245 |
| 33 | -347938 |
| 34 | 475036 |
| 35 | -646676 |
| 36 | 878145 |
| 37 | -1189468 |
| 38 | 1607095 |
| 39 | -2166672 |
| 40 | 2913794 |