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 | 5 |
| 3 | 17 |
| 4 | 49 |
| 5 | 129 |
| 6 | 321 |
| 7 | 769 |
| 8 | 1793 |
| 9 | 4097 |
| 10 | 9217 |
| 11 | 20481 |
| 12 | 45057 |
| 13 | 98305 |
| 14 | 212993 |
| 15 | 458753 |
| 16 | 983041 |
| 17 | 2097153 |
| 18 | 4456449 |
| 19 | 9437185 |
| 20 | 19922945 |
| 21 | 41943041 |
| 22 | 88080385 |
| 23 | 184549377 |
| 24 | 385875969 |
| 25 | 805306369 |
| 26 | 1677721601 |
| 27 | 3489660929 |
| 28 | 7247757313 |
| 29 | 15032385537 |
| 30 | 31138512897 |
| 31 | 64424509441 |