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 | 2 |
| 2 | 6 |
| 3 | 23 |
| 4 | 106 |
| 5 | 572 |
| 6 | 3564 |
| 7 | 25377 |
| 8 | 204446 |
| 9 | 1844876 |
| 10 | 18465556 |
| 11 | 203179902 |
| 12 | 2438366836 |
| 13 | 31699511768 |
| 14 | 443795839192 |
| 15 | 6656947282725 |
| 16 | 106511191881270 |
| 17 | 1810690391626380 |
| 18 | 32592427526913540 |
| 19 | 619256124778620450 |
| 20 | 12385122502136529420 |
| 21 | 260087572569333384840 |