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 | 2 |
| 1 | 7 |
| 2 | 29 |
| 3 | 133 |
| 4 | 641 |
| 5 | 3157 |
| 6 | 15689 |
| 7 | 78253 |
| 8 | 390881 |
| 9 | 1953637 |
| 10 | 9766649 |
| 11 | 48830173 |
| 12 | 244144721 |
| 13 | 1220711317 |
| 14 | 6103532009 |
| 15 | 30517610893 |
| 16 | 152587956161 |
| 17 | 762939584197 |
| 18 | 3814697527769 |
| 19 | 19073486852413 |
| 20 | 95367432689201 |
| 21 | 476837160300277 |