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 | 15 |
| 2 | 89 |
| 3 | 603 |
| 4 | 4433 |
| 5 | 34035 |
| 6 | 266969 |
| 7 | 2115723 |
| 8 | 16849313 |
| 9 | 134499555 |
| 10 | 1074849449 |
| 11 | 8594306043 |
| 12 | 68736785393 |
| 13 | 549824517075 |
| 14 | 4398319729529 |
| 15 | 35185460179563 |
| 16 | 281479314724673 |
| 17 | 2251817122694595 |
| 18 | 18014467616379209 |
| 19 | 144115464116024283 |