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 | 2 |
| 2 | 1 |
| 3 | 2 |
| 4 | 6 |
| 5 | 12 |
| 6 | 28 |
| 7 | 56 |
| 8 | 120 |
| 9 | 240 |
| 10 | 496 |
| 11 | 992 |
| 12 | 2016 |
| 13 | 4032 |
| 14 | 8128 |
| 15 | 16256 |
| 16 | 32640 |
| 17 | 65280 |
| 18 | 130816 |
| 19 | 261632 |
| 20 | 523776 |
| 21 | 1047552 |
| 22 | 2096128 |
| 23 | 4192256 |
| 24 | 8386560 |
| 25 | 16773120 |
| 26 | 33550336 |
| 27 | 67100672 |
| 28 | 134209536 |
| 29 | 268419072 |
| 30 | 536854528 |