yaworsw/euler-manager

---
:id: 386
:name: Maximum length of an antichain
:url: https://projecteuler.net/problem=386
:content: "Let <var>n</var> be an integer and <var>S</var>(<var>n</var>) be the set
  of factors of <var>n</var>.\n\nA subset <var>A</var> of <var>S</var>(<var>n</var>)
  is called an **antichain** of <var>S</var>(<var>n</var>) if <var>A</var> contains
  only one element or if none of the elements of <var>A</var> divides any of the other
  elements of <var>A</var>.\n\nFor example: <var>S</var>(30) = {1, 2, 3, 5, 6, 10,
  15, 30}  \n{2, 5, 6} is not an antichain of <var>S</var>(30).  \n{2, 3, 5} is an
  antichain of <var>S</var>(30).\n\nLet <var>N</var>(<var>n</var>) be the maximum
  length of an antichain of <var>S</var>(<var>n</var>).\n\nFind Σ<var>N</var>(<var>n</var>)
  for 1 ≤ <var>n</var> ≤ 10<sup>8</sup>\n\n"