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 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 8 |
| 4 | 18 |
| 5 | 44 |
| 6 | 110 |
| 7 | 272 |
| 8 | 662 |
| 9 | 1596 |
| 10 | 3838 |
| 11 | 9240 |
| 12 | 22286 |
| 13 | 53812 |
| 14 | 129974 |
| 15 | 313888 |
| 16 | 757878 |
| 17 | 1829644 |
| 18 | 4416910 |
| 19 | 10662952 |
| 20 | 25742302 |
| 21 | 62147556 |
| 22 | 150038438 |
| 23 | 362226480 |
| 24 | 874493446 |
| 25 | 2111213372 |
| 26 | 5096916094 |
| 27 | 12305037368 |
| 28 | 29706982638 |
| 29 | 71719002644 |
| 30 | 173145004310 |
| 31 | 418009044032 |