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 | 4 |
| 2 | 22 |
| 3 | 112 |
| 4 | 618 |
| 5 | 3044 |
| 6 | 14026 |
| 7 | 70340 |
| 8 | 347074 |
| 9 | 1713820 |
| 10 | 8430362 |
| 11 | 41516292 |
| 12 | 204628626 |
| 13 | 1008216460 |
| 14 | 4967464650 |
| 15 | 24473678612 |
| 16 | 120581823170 |
| 17 | 594106884060 |
| 18 | 2927147525626 |
| 19 | 14421969381220 |
| 20 | 71056635221618 |
| 21 | 350094259434668 |
| 22 | 1724905262555178 |
| 23 | 8498562511858612 |