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 | 3 |
| 1 | 13 |
| 2 | 73 |
| 3 | 433 |
| 4 | 2593 |
| 5 | 15553 |
| 6 | 93313 |
| 7 | 559873 |
| 8 | 3359233 |
| 9 | 20155393 |
| 10 | 120932353 |
| 11 | 725594113 |
| 12 | 4353564673 |
| 13 | 26121388033 |
| 14 | 156728328193 |
| 15 | 940369969153 |
| 16 | 5642219814913 |
| 17 | 33853318889473 |
| 18 | 203119913336833 |
| 19 | 1218719480020993 |
| 20 | 7312316880125953 |
| 21 | 43873901280755713 |