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 | 0 |
| 2 | 540 |
| 3 | 5940 |
| 4 | 54540 |
| 5 | 59940 |
| 6 | 540540 |
| 7 | 599940 |
| 8 | 5400540 |
| 9 | 5454540 |
| 10 | 5945940 |
| 11 | 5999940 |
| 12 | 54000540 |
| 13 | 54594540 |
| 14 | 59405940 |
| 15 | 59999940 |
| 16 | 540000540 |
| 17 | 540540540 |
| 18 | 545454540 |
| 19 | 545994540 |
| 20 | 594005940 |
| 21 | 594545940 |
| 22 | 599459940 |
| 23 | 599999940 |
| 24 | 5400000540 |
| 25 | 5405940540 |
| 26 | 5454054540 |
| 27 | 5459994540 |
| 28 | 5940005940 |
| 29 | 5945945940 |
| 30 | 5994059940 |
| 31 | 5999999940 |