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 | 3 |
| 3 | 13 |
| 4 | 76 |
| 5 | 551 |
| 6 | 4803 |
| 7 | 48833 |
| 8 | 567465 |
| 9 | 7418263 |
| 10 | 107752293 |
| 11 | 1721642143 |
| 12 | 30008756055 |
| 13 | 566650322031 |
| 14 | 11523037802461 |
| 15 | 251062618129063 |
| 16 | 5834798259848815 |
| 17 | 144078299659541361 |
| 18 | 3766993649599221903 |
| 19 | 103961442644871088897 |
| 20 | 3020133228180079209075 |