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 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 12 |
| 4 | 148 |
| 5 | 21909 |
| 6 | 480004287 |
| 7 | 230404115538378376 |
| 8 | 53086056457022411804685755744397384 |
| 9 | 2818129390158170901506703075470572449397357853477615482257305306043465 |