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 | 1 |
| 1 | 7 |
| 2 | 21 |
| 3 | 127 |
| 4 | 381 |
| 5 | 1911 |
| 6 | 5461 |
| 7 | 32767 |
| 8 | 98301 |
| 9 | 491511 |
| 10 | 1408981 |
| 11 | 8355711 |
| 12 | 25001341 |
| 13 | 125269879 |
| 14 | 357913941 |
| 15 | 2147483647 |
| 16 | 6442450941 |
| 17 | 32212254711 |
| 18 | 92341796821 |
| 19 | 547608330111 |
| 20 | 1638530022781 |
| 21 | 8209829984119 |
| 22 | 23456963876181 |
| 23 | 140735340838911 |
| 24 | 422201727483901 |