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 | 1 |
| 2 | -2 |
| 3 | 3 |
| 4 | -4 |
| 5 | 6 |
| 6 | -10 |
| 7 | 15 |
| 8 | -20 |
| 9 | 30 |
| 10 | -52 |
| 11 | 78 |
| 12 | -96 |
| 13 | 144 |
| 14 | -282 |
| 15 | 423 |
| 16 | -420 |
| 17 | 630 |
| 18 | -1660 |
| 19 | 2490 |
| 20 | -1304 |
| 21 | 1956 |
| 22 | -11332 |
| 23 | 16998 |
| 24 | 3896 |
| 25 | -5844 |
| 26 | -95240 |
| 27 | 142860 |
| 28 | 157160 |
| 29 | -235740 |
| 30 | -983610 |
| 31 | 1475415 |
| 32 | 2634300 |
| 33 | -3951450 |
| 34 | -11751660 |
| 35 | 17627490 |
| 36 | 38381160 |
| 37 | -57571740 |