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 | -2 |
| 2 | 2 |
| 3 | -4 |
| 4 | 6 |
| 5 | -8 |
| 6 | 12 |
| 7 | -16 |
| 8 | 22 |
| 9 | -28 |
| 10 | 36 |
| 11 | -48 |
| 12 | 60 |
| 13 | -76 |
| 14 | 96 |
| 15 | -120 |
| 16 | 150 |
| 17 | -184 |
| 18 | 228 |
| 19 | -280 |
| 20 | 340 |
| 21 | -416 |
| 22 | 504 |
| 23 | -608 |
| 24 | 732 |
| 25 | -878 |
| 26 | 1052 |
| 27 | -1252 |
| 28 | 1488 |
| 29 | -1768 |
| 30 | 2088 |
| 31 | -2464 |
| 32 | 2902 |
| 33 | -3408 |
| 34 | 3996 |
| 35 | -4672 |
| 36 | 5460 |
| 37 | -6364 |
| 38 | 7400 |
| 39 | -8600 |
| 40 | 9972 |
| 41 | -11544 |
| 42 | 13344 |
| 43 | -15400 |
| 44 | 17752 |
| 45 | -20424 |