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 | 33 |
| 2 | 99 |
| 3 | 2121 |
| 4 | 2323 |
| 5 | 5151 |
| 6 | 5959 |
| 7 | 6363 |
| 8 | 7171 |
| 9 | 7575 |
| 10 | 8787 |
| 11 | 8989 |
| 12 | 9999 |
| 13 | 105105 |
| 14 | 111111 |
| 15 | 117117 |
| 16 | 123123 |
| 17 | 129129 |
| 18 | 135135 |
| 19 | 143143 |
| 20 | 147147 |
| 21 | 153153 |
| 22 | 171171 |
| 23 | 173173 |
| 24 | 177177 |
| 25 | 191191 |
| 26 | 201201 |
| 27 | 237237 |
| 28 | 243243 |
| 29 | 255255 |
| 30 | 263263 |
| 31 | 285285 |
| 32 | 305305 |
| 33 | 309309 |
| 34 | 317317 |