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 | 4 |
| 2 | 25 |
| 3 | 260 |
| 4 | 3205 |
| 5 | 42966 |
| 6 | 609567 |
| 7 | 8999164 |
| 8 | 136811781 |
| 9 | 2127343669 |
| 10 | 33675622992 |
| 11 | 540878965522 |
| 12 | 8792433396559 |
| 13 | 144383416380703 |
| 14 | 2391557494237062 |
| 15 | 39910530610590312 |
| 16 | 670383542665237001 |
| 17 | 11325278943044058378 |
| 18 | 192301381444863249559 |
| 19 | 3280101940070399446926 |