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id	title	challengeType	forumTopicId	dashedName
5900f4ed1000cf542c50ffff	Problem 383: Divisibility comparison between factorials	5	302047	problem-383-divisibility-comparison-between-factorials

--description--

Let f5(n) be the largest integer x for which 5x divides n.

For example, f5(625000) = 7.

Let T5(n) be the number of integers i which satisfy f5((2·i-1)!) < 2·f5(i!) and 1 ≤ i ≤ n. It can be verified that T5(103) = 68 and T5(109) = 2408210.

Find T5(1018).

--hints--

euler383() should return 22173624649806.

assert.strictEqual(euler383(), 22173624649806);

--seed--

--seed-contents--

function euler383() {

  return true;
}

euler383();

--solutions--

// solution required

756 B Raw Blame History