English
Let n = 70. Then n is weird: it is abundant but not pseudoperfect.
Русский
Пусть n = 70. Это странное число: избыточное, но не псевдоперфектное.
LaTeX
$$$\\operatorname{Abundant}(70) \\land \\neg \\operatorname{Pseudoperfect}(70)$$$
Lean4
theorem weird_seventy : Weird 70 :=
by
rw [Weird, Abundant, not_pseudoperfect_iff_forall]
have h : properDivisors 70 = { 1, 2, 5, 7, 10, 14, 35 } := by rfl
constructor
· rw [h]
repeat norm_num
· rw [h]
right
intro s hs
have hs' := mem_powerset.mpr hs
fin_cases hs' <;> decide