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 | 7 |
| 3 | 57 |
| 4 | 484 |
| 5 | 4199 |
| 6 | 36938 |
| 7 | 328185 |
| 8 | 2937932 |
| 9 | 26457508 |
| 10 | 239414383 |
| 11 | 2175127695 |
| 12 | 19827974412 |
| 13 | 181266501290 |
| 14 | 1661241473220 |
| 15 | 15257624681145 |
| 16 | 140400178555644 |
| 17 | 1294141164447692 |
| 18 | 11946771748196428 |
| 19 | 110435320379615620 |
| 20 | 1022108852175416720 |
| 21 | 9470416604629933935 |