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) |
|---|---|
| 1 | 9 |
| 2 | 45 |
| 3 | 3 |
| 4 | 225 |
| 5 | 18 |
| 6 | 15 |
| 7 | -1 |
| 8 | 1125 |
| 9 | 1 |
| 10 | 99 |
| 11 | 495 |
| 12 | 33 |
| 13 | 2475 |
| 14 | 198 |
| 15 | 165 |
| 16 | -1 |
| 17 | 12375 |
| 18 | 11 |
| 19 | 999 |
| 20 | 4995 |
| 21 | 333 |
| 22 | 24975 |
| 23 | 1998 |
| 24 | 1665 |
| 25 | -1 |
| 26 | 124875 |
| 27 | 111 |
| 28 | 9999 |
| 29 | 49995 |
| 30 | 3333 |
| 31 | 249975 |
| 32 | 19998 |
| 33 | 16665 |
| 34 | -1 |
| 35 | 1249875 |
| 36 | 1111 |
| 37 | 99999 |
| 38 | 49995 |
| 39 | 33333 |
| 40 | 2499975 |
| 41 | 199998 |
| 42 | 166665 |
| 43 | -1 |
| 44 | 12499875 |
| 45 | 11111 |
| 46 | 999999 |
| 47 | 4999995 |
| 48 | 333333 |
| 49 | 24999975 |
| 50 | 1999998 |
| 51 | 1666665 |
| 52 | -1 |
| 53 | 124999875 |
| 54 | 111111 |