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 | -4 |
| 1 | -3 |
| 2 | -1 |
| 3 | 3 |
| 4 | 11 |
| 5 | 27 |
| 6 | 59 |
| 7 | 123 |
| 8 | 251 |
| 9 | 507 |
| 10 | 1019 |
| 11 | 2043 |
| 12 | 4091 |
| 13 | 8187 |
| 14 | 16379 |
| 15 | 32763 |
| 16 | 65531 |
| 17 | 131067 |
| 18 | 262139 |
| 19 | 524283 |
| 20 | 1048571 |
| 21 | 2097147 |
| 22 | 4194299 |
| 23 | 8388603 |
| 24 | 16777211 |
| 25 | 33554427 |
| 26 | 67108859 |
| 27 | 134217723 |
| 28 | 268435451 |
| 29 | 536870907 |
| 30 | 1073741819 |
| 31 | 2147483643 |