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 | 2 |
| 1 | -1 |
| 2 | 2 |
| 3 | -4 |
| 4 | 7 |
| 5 | -12 |
| 6 | 22 |
| 7 | -41 |
| 8 | 74 |
| 9 | -133 |
| 10 | 243 |
| 11 | -444 |
| 12 | 806 |
| 13 | -1465 |
| 14 | 2669 |
| 15 | -4859 |
| 16 | 8840 |
| 17 | -16087 |
| 18 | 29282 |
| 19 | -53296 |
| 20 | 96994 |
| 21 | -176527 |
| 22 | 321290 |
| 23 | -584755 |
| 24 | 1064251 |
| 25 | -1936952 |
| 26 | 3525296 |
| 27 | -6416092 |
| 28 | 11677369 |
| 29 | -21252993 |
| 30 | 38680798 |
| 31 | -70399646 |
| 32 | 128128414 |
| 33 | -233195704 |
| 34 | 424419826 |
| 35 | -772450633 |
| 36 | 1405872057 |
| 37 | -2558708924 |
| 38 | 4656889892 |
| 39 | -8475611623 |
| 40 | 15425744240 |
| 41 | -28075093283 |
| 42 | 51097104306 |
| 43 | -92997520459 |
| 44 | 169256926243 |
| 45 | -308050225082 |
| 46 | 560656176744 |
| 47 | -1020402917484 |
| 48 | 1857149100126 |
| 49 | -3380040101304 |
| 50 | 6151725289638 |