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 | 0 |
| 2 | 1 |
| 3 | 3 |
| 4 | 9 |
| 5 | 21 |
| 6 | 51 |
| 7 | 111 |
| 8 | 237 |
| 9 | 489 |
| 10 | 995 |
| 11 | 2017 |
| 12 | 4059 |
| 13 | 8151 |
| 14 | 16341 |
| 15 | 32721 |
| 16 | 65483 |
| 17 | 131013 |
| 18 | 262083 |
| 19 | 524221 |
| 20 | 1048505 |
| 21 | 2097079 |
| 22 | 4194225 |
| 23 | 8388525 |
| 24 | 16777127 |
| 25 | 33554335 |
| 26 | 67108763 |
| 27 | 134217625 |
| 28 | 268435349 |
| 29 | 536870803 |
| 30 | 1073741711 |
| 31 | 2147483521 |
| 32 | 4294967165 |
| 33 | 8589934455 |
| 34 | 17179869045 |