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 | 45 |
| 2 | 495 |
| 3 | 4545 |
| 4 | 4995 |
| 5 | 45045 |
| 6 | 49995 |
| 7 | 450045 |
| 8 | 454545 |
| 9 | 495495 |
| 10 | 499995 |
| 11 | 4500045 |
| 12 | 4549545 |
| 13 | 4950495 |
| 14 | 4999995 |
| 15 | 45000045 |
| 16 | 45045045 |
| 17 | 45454545 |
| 18 | 45499545 |
| 19 | 49500495 |
| 20 | 49545495 |
| 21 | 49954995 |
| 22 | 49999995 |
| 23 | 450000045 |
| 24 | 450495045 |
| 25 | 454504545 |
| 26 | 454999545 |
| 27 | 495000495 |
| 28 | 495495495 |
| 29 | 499504995 |