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 | 2 |
| 2 | 10 |
| 3 | 42 |
| 4 | 170 |
| 5 | 682 |
| 6 | 2730 |
| 7 | 10922 |
| 8 | 43690 |
| 9 | 174762 |
| 10 | 699050 |
| 11 | 2796202 |
| 12 | 11184810 |
| 13 | 44739242 |
| 14 | 178956970 |
| 15 | 715827882 |
| 16 | 2863311530 |
| 17 | 11453246122 |
| 18 | 45812984490 |
| 19 | 183251937962 |
| 20 | 733007751850 |
| 21 | 2932031007402 |
| 22 | 11728124029610 |
| 23 | 46912496118442 |
| 24 | 187649984473770 |
| 25 | 750599937895082 |