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) |
|---|---|
| 1 | 0 |
| 2 | 6 |
| 3 | 26 |
| 4 | 206 |
| 5 | 1100 |
| 6 | 7314 |
| 7 | 42920 |
| 8 | 274010 |
| 9 | 1677332 |
| 10 | 10616070 |
| 11 | 66290046 |
| 12 | 419754586 |
| 13 | 2648500908 |
| 14 | 16818685050 |
| 15 | 106781976774 |
| 16 | 680250643910 |
| 17 | 4337083126232 |
| 18 | 27709045093274 |
| 19 | 177213890858938 |
| 20 | 1135003956744310 |
| 21 | 7276652578220372 |
| 22 | 46702733068082702 |
| 23 | 300013046145979184 |