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 | 4 |
| 2 | 21 |
| 3 | 114 |
| 4 | 616 |
| 5 | 3329 |
| 6 | 17991 |
| 7 | 97229 |
| 8 | 525456 |
| 9 | 2839729 |
| 10 | 15346786 |
| 11 | 82938844 |
| 12 | 448227521 |
| 13 | 2422362079 |
| 14 | 13091204281 |
| 15 | 70748973084 |
| 16 | 382349636061 |
| 17 | 2066337330754 |
| 18 | 11167134898976 |
| 19 | 60350698792449 |
| 20 | 326154101090951 |
| 21 | 1762639037938629 |
| 22 | 9525854090667496 |
| 23 | 51480702630305689 |
| 24 | 278217860370802066 |