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 | 1 |
| 2 | 13 |
| 3 | 107 |
| 4 | 838 |
| 5 | 6523 |
| 6 | 51420 |
| 7 | 396500 |
| 8 | 3086898 |
| 9 | 24009733 |
| 10 | 186735416 |
| 11 | 1452320952 |
| 12 | 11295996925 |
| 13 | 87852065113 |
| 14 | 683271518863 |
| 15 | 5314139902766 |
| 16 | 41330688551925 |
| 17 | 321449136734050 |
| 18 | 2500069029481412 |
| 19 | 19444268928224485 |
| 20 | 151227677898412290 |
| 21 | 1176172285095334802 |