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 | 2 |
| 3 | 10 |
| 4 | 74 |
| 5 | 417 |
| 6 | 2614 |
| 7 | 16438 |
| 8 | 101622 |
| 9 | 633063 |
| 10 | 3941012 |
| 11 | 24511836 |
| 12 | 152535900 |
| 13 | 949133883 |
| 14 | 5905611508 |
| 15 | 36746590964 |
| 16 | 228646935796 |
| 17 | 1422699232325 |
| 18 | 8852413871022 |
| 19 | 55082039340022 |
| 20 | 342734883853750 |
| 21 | 2132586518002125 |