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 | 0 |
| 3 | 0 |
| 4 | 2 |
| 5 | 7157 |
| 6 | 1143638 |
| 7 | 44031035 |
| 8 | 771464278 |
| 9 | 8219304992 |
| 10 | 62114308624 |
| 11 | 364798895986 |
| 12 | 1765597908290 |
| 13 | 7329246973785 |
| 14 | 26849172347850 |
| 15 | 88645482921449 |
| 16 | 268042562131202 |
| 17 | 751635857876290 |
| 18 | 1974215715426992 |
| 19 | 4896315981217168 |
| 20 | 11542835604897814 |
| 21 | 26008912447737323 |