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 | 4 |
| 2 | 25 |
| 3 | 190 |
| 4 | 1570 |
| 5 | 13552 |
| 6 | 120178 |
| 7 | 1085620 |
| 8 | 9940345 |
| 9 | 91962460 |
| 10 | 857750233 |
| 11 | 8053389142 |
| 12 | 76026759760 |
| 13 | 721017894640 |
| 14 | 6864725124520 |
| 15 | 65578937628304 |
| 16 | 628320730656586 |
| 17 | 6035594205744520 |
| 18 | 58110220504754650 |
| 19 | 560624083417180300 |
| 20 | 5418599393597801020 |
| 21 | 52459116546784350880 |