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 | 2 |
| 2 | 10 |
| 3 | 58 |
| 4 | 370 |
| 5 | 2514 |
| 6 | 17850 |
| 7 | 130890 |
| 8 | 983650 |
| 9 | 7536418 |
| 10 | 58648810 |
| 11 | 462306266 |
| 12 | 3683602130 |
| 13 | 29620138994 |
| 14 | 240059315610 |
| 15 | 1958940281322 |
| 16 | 16081662931650 |
| 17 | 132723191430210 |
| 18 | 1100568370427850 |
| 19 | 9164925012016506 |
| 20 | 76612776253995570 |