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 | 0 |
| 2 | 511 |
| 3 | 19682 |
| 4 | 262143 |
| 5 | 1953124 |
| 6 | 10077695 |
| 7 | 40353606 |
| 8 | 134217727 |
| 9 | 387420488 |
| 10 | 999999999 |
| 11 | 2357947690 |
| 12 | 5159780351 |
| 13 | 10604499372 |
| 14 | 20661046783 |
| 15 | 38443359374 |
| 16 | 68719476735 |
| 17 | 118587876496 |
| 18 | 198359290367 |
| 19 | 322687697778 |
| 20 | 511999999999 |
| 21 | 794280046580 |
| 22 | 1207269217791 |
| 23 | 1801152661462 |