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 | 2 |
| 3 | -5 |
| 4 | 9 |
| 5 | -18 |
| 6 | 37 |
| 7 | -73 |
| 8 | 146 |
| 9 | -293 |
| 10 | 585 |
| 11 | -1170 |
| 12 | 2341 |
| 13 | -4681 |
| 14 | 9362 |
| 15 | -18725 |
| 16 | 37449 |
| 17 | -74898 |
| 18 | 149797 |
| 19 | -299593 |
| 20 | 599186 |
| 21 | -1198373 |
| 22 | 2396745 |
| 23 | -4793490 |
| 24 | 9586981 |
| 25 | -19173961 |
| 26 | 38347922 |
| 27 | -76695845 |
| 28 | 153391689 |
| 29 | -306783378 |
| 30 | 613566757 |
| 31 | -1227133513 |
| 32 | 2454267026 |
| 33 | -4908534053 |
| 34 | 9817068105 |