Erdős Problem 361 #
Reference: erdosproblems.com/361
theorem
erdos_361.bigO
(c : ℝ)
(hc : 0 < c)
(A : ℕ → ℕ)
(hA :
∀ (c n : ℕ),
A n = (Finset.filter (fun (B : Finset ℕ) => n ≠ ∑ a ∈ B, a) (Finset.Icc 1 ⌊c * n⌋₊).powerset).sup Finset.card)
:
Let $c>0$ and $n$ be some large integer. What is the size of the largest $A\subseteq \{1,\ldots,\lfloor cn\rfloor\}$ such that $n$ is not a sum of a subset of $A$? Does this depend on $n$ in an irregular way?
theorem
erdos_361.bigTheta
(c : ℝ)
(hc : 0 < c)
(A : ℕ → ℕ)
(hA :
∀ (c n : ℕ),
A n = (Finset.filter (fun (B : Finset ℕ) => n ≠ ∑ a ∈ B, a) (Finset.Icc 1 ⌊c * n⌋₊).powerset).sup Finset.card)
:
Let $c>0$ and $n$ be some large integer. What is the size of the largest $A\subseteq \{1,\ldots,\lfloor cn\rfloor\}$ such that $n$ is not a sum of a subset of $A$? Does this depend on $n$ in an irregular way?
theorem
erdos_361.smallO
(c : ℝ)
(hc : 0 < c)
(A : ℕ → ℕ)
(hA :
∀ (c n : ℕ),
A n = (Finset.filter (fun (B : Finset ℕ) => n ≠ ∑ a ∈ B, a) (Finset.Icc 1 ⌊c * n⌋₊).powerset).sup Finset.card)
:
Let $c>0$ and $n$ be some large integer. What is the size of the largest $A\subseteq \{1,\ldots,\lfloor cn\rfloor\}$ such that $n$ is not a sum of a subset of $A$? Does this depend on $n$ in an irregular way?