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 | 21 |
| 2 | 99 |
| 3 | 369 |
| 4 | 1607 |
| 5 | 7051 |
| 6 | 31743 |
| 7 | 144683 |
| 8 | 666527 |
| 9 | 3094947 |
| 10 | 14463569 |
| 11 | 67946603 |
| 12 | 320593259 |
| 13 | 1518250599 |
| 14 | 7212838277 |
| 15 | 34360479199 |
| 16 | 164079145839 |
| 17 | 785173661987 |
| 18 | 3764380920489 |
| 19 | 18077996769707 |
| 20 | 86948519336037 |
| 21 | 418760656546517 |