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 | 12 |
| 2 | 120 |
| 3 | 1128 |
| 4 | 10344 |
| 5 | 93864 |
| 6 | 847848 |
| 7 | 7642920 |
| 8 | 68835432 |
| 9 | 619715496 |
| 10 | 5578225896 |
| 11 | 50207178792 |
| 12 | 451877192040 |
| 13 | 4066945060008 |
| 14 | 36602706866664 |
| 15 | 329425167106344 |
| 16 | 2964829725182568 |
| 17 | 26683480411545000 |
| 18 | 240151375243512552 |
| 19 | 2161362583350043176 |
| 20 | 19452264074784109416 |