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 | 54 |
| 3 | 490 |
| 4 | 4050 |
| 5 | 32674 |
| 6 | 261954 |
| 7 | 2096770 |
| 8 | 16776450 |
| 9 | 134216194 |
| 10 | 1073738754 |
| 11 | 8589928450 |
| 12 | 68719464450 |
| 13 | 549755789314 |
| 14 | 4398046461954 |
| 15 | 35184371990530 |
| 16 | 281474976514050 |
| 17 | 2251799813292034 |
| 18 | 18014398508695554 |
| 19 | 144115188074283010 |
| 20 | 1152921504603701250 |