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 | 55 |
| 2 | 66 |
| 3 | 5050 |
| 4 | 5151 |
| 5 | 203203 |
| 6 | 255255 |
| 7 | 426426 |
| 8 | 500500 |
| 9 | 501501 |
| 10 | 581581 |
| 11 | 828828 |
| 12 | 930930 |
| 13 | 39653965 |
| 14 | 50005000 |
| 15 | 50015001 |
| 16 | 61566156 |
| 17 | 3347133471 |
| 18 | 5000050000 |
| 19 | 5000150001 |
| 20 | 6983669836 |
| 21 | 220028220028 |
| 22 | 500000500000 |
| 23 | 500001500001 |