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 | 1 |
| 2 | 5 |
| 3 | 23 |
| 4 | 139 |
| 5 | 1052 |
| 6 | 9166 |
| 7 | 90073 |
| 8 | 989205 |
| 9 | 11981051 |
| 10 | 158149438 |
| 11 | 2255926638 |
| 12 | 34549223880 |
| 13 | 564898101239 |
| 14 | 9812669832553 |
| 15 | 180324597042263 |
| 16 | 3492960489714519 |
| 17 | 71092066388237562 |
| 18 | 1516044005669227542 |
| 19 | 33788707128788508476 |
| 20 | 785270646437483414261 |
| 21 | 18992014442689191510460 |