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) |
|---|---|
| 1 | 7 |
| 2 | 49 |
| 3 | 315 |
| 4 | 1981 |
| 5 | 12327 |
| 6 | 76237 |
| 7 | 469623 |
| 8 | 2884909 |
| 9 | 17686215 |
| 10 | 108259885 |
| 11 | 661872471 |
| 12 | 4042575277 |
| 13 | 24671450343 |
| 14 | 150466937773 |
| 15 | 917151735159 |
| 16 | 5587651325485 |
| 17 | 34027698639111 |
| 18 | 207144227712301 |
| 19 | 1260572274312087 |
| 20 | 7668877406965933 |