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 | 19 |
| 2 | 29 |
| 3 | -1 |
| 4 | 499 |
| 5 | 59 |
| 6 | -1 |
| 7 | 79 |
| 8 | 89 |
| 9 | -1 |
| 10 | 109 |
| 11 | 1199999 |
| 12 | -1 |
| 13 | 139 |
| 14 | 149 |
| 15 | -1 |
| 16 | 1699 |
| 17 | 179 |
| 18 | -1 |
| 19 | 199 |
| 20 | 2099 |
| 21 | -1 |
| 22 | 229 |
| 23 | 239 |
| 24 | -1 |
| 25 | 25999 |
| 26 | 269 |
| 27 | -1 |
| 28 | 289999 |
| 29 | 2999 |
| 30 | -1 |
| 31 | 319999999999999999999999999999 |
| 32 | 3299 |
| 33 | -1 |
| 34 | 349 |
| 35 | 359 |
| 36 | -1 |
| 37 | 379 |
| 38 | 389 |
| 39 | -1 |
| 40 | 409 |
| 41 | 419 |
| 42 | -1 |
| 43 | 439 |
| 44 | 449 |
| 45 | -1 |