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 | 451 |
| 2 | 1353 |
| 3 | 2981 |
| 4 | 4059 |
| 5 | 8943 |
| 6 | 9091 |
| 7 | 26829 |
| 8 | 27273 |
| 9 | 81819 |
| 10 | 100001 |
| 11 | 122221 |
| 12 | 300003 |
| 13 | 366663 |
| 14 | 372731 |
| 15 | 900009 |
| 16 | 1099989 |
| 17 | 1118193 |
| 18 | 2463661 |
| 19 | 3354579 |
| 20 | 4100041 |
| 21 | 7390983 |
| 22 | 12300123 |
| 23 | 22172949 |
| 24 | 27100271 |
| 25 | 36900369 |
| 26 | 81300813 |
| 27 | 101010101 |
| 28 | 243902439 |
| 29 | 303030303 |
| 30 | 909090909 |
| 31 | 1111111111 |
| 32 | 3333333333 |
| 33 | 9999999999 |