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 | 3 |
| 2 | 6 |
| 3 | 13 |
| 4 | 28 |
| 5 | 59 |
| 6 | 122 |
| 7 | 249 |
| 8 | 504 |
| 9 | 1015 |
| 10 | 2038 |
| 11 | 4085 |
| 12 | 8180 |
| 13 | 16371 |
| 14 | 32754 |
| 15 | 65521 |
| 16 | 131056 |
| 17 | 262127 |
| 18 | 524270 |
| 19 | 1048557 |
| 20 | 2097132 |
| 21 | 4194283 |
| 22 | 8388586 |
| 23 | 16777193 |
| 24 | 33554408 |
| 25 | 67108839 |
| 26 | 134217702 |
| 27 | 268435429 |
| 28 | 536870884 |
| 29 | 1073741795 |
| 30 | 2147483618 |