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 | 7 |
| 3 | 53 |
| 4 | 491 |
| 5 | 6451 |
| 6 | 97723 |
| 7 | 1871501 |
| 8 | 39642599 |
| 9 | 999076987 |
| 10 | 31204161323 |
| 11 | 1038495626543 |
| 12 | 40831064063651 |
| 13 | 1770543222362221 |
| 14 | 80392862250956443 |
| 15 | 3974705945770003271 |
| 16 | 220497651647226035923 |
| 17 | 13563377141298566879867 |
| 18 | 861975691921988407175147 |
| 19 | 59980850604601955729416979 |