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) |
|---|---|
| 1 | -1 |
| 2 | 3 |
| 3 | -6 |
| 4 | 10 |
| 5 | -15 |
| 6 | 21 |
| 7 | -28 |
| 8 | 36 |
| 9 | -45 |
| 10 | 55 |
| 11 | -66 |
| 12 | 78 |
| 13 | -91 |
| 14 | 105 |
| 15 | -120 |
| 16 | 136 |
| 17 | -153 |
| 18 | 171 |
| 19 | -190 |
| 20 | 210 |
| 21 | -231 |
| 22 | 253 |
| 23 | -276 |
| 24 | 300 |
| 25 | -325 |
| 26 | 351 |
| 27 | -378 |
| 28 | 406 |
| 29 | -435 |
| 30 | 465 |
| 31 | -496 |
| 32 | 528 |
| 33 | -561 |
| 34 | 595 |
| 35 | -630 |
| 36 | 666 |
| 37 | -703 |
| 38 | 741 |
| 39 | -780 |
| 40 | 820 |
| 41 | -861 |
| 42 | 903 |
| 43 | -946 |
| 44 | 990 |
| 45 | -1035 |
| 46 | 1081 |
| 47 | -1128 |
| 48 | 1176 |
| 49 | -1225 |
| 50 | 1275 |