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.
{k=1..n} is an n-tuple of nonnegative integers such that Sum's wiki page.
{k=1..n} is an n-tuple of nonnegative integers such that Sum has authored 0 sequences.