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} * (-2)^(n-1) * hyergeometric1f1(1-n; -2*n; -2), where (a)'s wiki page.
{n} * (-2)^(n-1) * hyergeometric1f1(1-n; -2*n; -2), where (a) has authored 0 sequences.