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 | 0 |
| 1 | 2 |
| 2 | 22 |
| 3 | 142 |
| 4 | 734 |
| 5 | 3390 |
| 6 | 14718 |
| 7 | 61694 |
| 8 | 253438 |
| 9 | 1029118 |
| 10 | 4151294 |
| 11 | 16683006 |
| 12 | 66904062 |
| 13 | 267993086 |
| 14 | 1072791550 |
| 15 | 4292935678 |
| 16 | 17175543806 |
| 17 | 68710301694 |
| 18 | 274858508286 |
| 19 | 1099470733310 |
| 20 | 4397960527870 |
| 21 | 17592005689342 |
| 22 | 70368366690302 |
| 23 | 281474188181502 |
| 24 | 1125898262675454 |
| 25 | 4503596204818430 |
| 26 | 18014391395942398 |