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 | 1 |
| 2 | 3 |
| 3 | 25 |
| 4 | 253 |
| 5 | 3121 |
| 6 | 46651 |
| 7 | 823537 |
| 8 | 16777209 |
| 9 | 387420481 |
| 10 | 9999999991 |
| 11 | 285311670601 |
| 12 | 8916100448245 |
| 13 | 302875106592241 |
| 14 | 11112006825558003 |
| 15 | 437893890380859361 |
| 16 | 18446744073709551601 |
| 17 | 827240261886336764161 |
| 18 | 39346408075296537575407 |
| 19 | 1978419655660313589123961 |