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 | 12 |
| 3 | 54 |
| 4 | 224 |
| 5 | 906 |
| 6 | 3636 |
| 7 | 14558 |
| 8 | 58248 |
| 9 | 233010 |
| 10 | 932060 |
| 11 | 3728262 |
| 12 | 14913072 |
| 13 | 59652314 |
| 14 | 238609284 |
| 15 | 954437166 |
| 16 | 3817748696 |
| 17 | 15270994818 |
| 18 | 61083979308 |
| 19 | 244335917270 |
| 20 | 977343669120 |
| 21 | 3909374676522 |
| 22 | 15637498706132 |
| 23 | 62549994824574 |