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 | 57 |
| 3 | 493 |
| 4 | 4053 |
| 5 | 32677 |
| 6 | 261957 |
| 7 | 2096773 |
| 8 | 16776453 |
| 9 | 134216197 |
| 10 | 1073738757 |
| 11 | 8589928453 |
| 12 | 68719464453 |
| 13 | 549755789317 |
| 14 | 4398046461957 |
| 15 | 35184371990533 |
| 16 | 281474976514053 |
| 17 | 2251799813292037 |
| 18 | 18014398508695557 |
| 19 | 144115188074283013 |
| 20 | 1152921504603701253 |
| 21 | 9223372036848484357 |