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) |
|---|---|
| 2 | 3 |
| 3 | 23 |
| 4 | 251 |
| 5 | 3121 |
| 6 | 46649 |
| 7 | 823541 |
| 8 | 16777213 |
| 9 | 387420479 |
| 10 | 9999999967 |
| 11 | 285311670569 |
| 12 | 8916100448237 |
| 13 | 302875106592241 |
| 14 | 11112006825557999 |
| 15 | 437893890380859323 |
| 16 | 18446744073709551557 |
| 17 | 827240261886336764159 |
| 18 | 39346408075296537575359 |