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) |
|---|---|
| 0 | 1 |
| 1 | 10 |
| 2 | 110 |
| 3 | 990 |
| 4 | 8195 |
| 5 | 62854 |
| 6 | 455675 |
| 7 | 3147210 |
| 8 | 20874205 |
| 9 | 133650330 |
| 10 | 829656124 |
| 11 | 5010237850 |
| 12 | 29516429335 |
| 13 | 170025614980 |
| 14 | 959521900370 |
| 15 | 5313793679524 |
| 16 | 28919055049170 |
| 17 | 154857622067610 |
| 18 | 816814457097155 |
| 19 | 4247904244224630 |
| 20 | 21800095116980345 |
| 21 | 110485969920692960 |