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 | 55 |
| 3 | 4005 |
| 4 | 5050 |
| 5 | 404550 |
| 6 | 405450 |
| 7 | 500500 |
| 8 | 40405555 |
| 9 | 40504500 |
| 10 | 50005000 |
| 11 | 454044045 |
| 12 | 500054500 |
| 13 | 4050045000 |
| 14 | 4540044405 |
| 15 | 5000050000 |
| 16 | 405000450000 |
| 17 | 455005054540 |
| 18 | 500000500000 |
| 19 | 40500004500000 |
| 20 | 50000005000000 |
| 21 | 50450455004040 |
| 22 | 540550504445050 |
| 23 | 4050000045000000 |