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 | 12 |
| 3 | 124 |
| 4 | 1248 |
| 5 | 12496 |
| 6 | 124992 |
| 7 | 1249984 |
| 8 | 12499968 |
| 9 | 124999936 |
| 10 | 1249999862 |
| 11 | 12499999623 |
| 12 | 124999998144 |
| 13 | 1249999984364 |
| 14 | 12499999840480 |
| 15 | 124999998308464 |
| 16 | 1249999981991936 |
| 17 | 12499999808733888 |
| 18 | 124999997974967808 |
| 19 | 1249999978624935680 |
| 20 | 12499999774999871588 |