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 | 1 |
| 2 | 49 |
| 3 | 229 |
| 4 | 1861 |
| 5 | 12001 |
| 6 | 84241 |
| 7 | 572209 |
| 8 | 3935569 |
| 9 | 26939221 |
| 10 | 184737301 |
| 11 | 1265964481 |
| 12 | 8677687969 |
| 13 | 59476087009 |
| 14 | 407659540081 |
| 15 | 2794128600901 |
| 16 | 19151272325221 |
| 17 | 131264694791329 |
| 18 | 899701808208049 |
| 19 | 6166647394567441 |
| 20 | 42266831441062801 |
| 21 | 289701168799073461 |