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 | 3 |
| 3 | 11 |
| 4 | 47 |
| 5 | 219 |
| 6 | 1081 |
| 7 | 5557 |
| 8 | 29439 |
| 9 | 159611 |
| 10 | 881405 |
| 11 | 4940385 |
| 12 | 28035205 |
| 13 | 160751005 |
| 14 | 929923395 |
| 15 | 5420717819 |
| 16 | 31809479855 |
| 17 | 187757573787 |
| 18 | 1114012352029 |
| 19 | 6640357243537 |
| 20 | 39746256802185 |
| 21 | 238796968208537 |
| 22 | 1439587364576015 |