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 | 1 |
| 2 | 4 |
| 3 | 34 |
| 4 | 216 |
| 5 | 1525 |
| 6 | 10336 |
| 7 | 71149 |
| 8 | 486864 |
| 9 | 3339106 |
| 10 | 22881100 |
| 11 | 156843721 |
| 12 | 1074985344 |
| 13 | 7368157369 |
| 14 | 50501844796 |
| 15 | 346145466850 |
| 16 | 2372514562656 |
| 17 | 16261461342589 |
| 18 | 111457702083424 |
| 19 | 763942486626661 |
| 20 | 5236139616899400 |