Problem Analysis #0

22.36s
5,313 toks
Problem Statement

For positive integers a,b,ca,b,c we say that the triple (a,b,c)(a,b,c) is \emph{cyclically divisible} if

a+1b,b+1c,c+1a\frac{a+1}{b},\quad \frac{b+1}{c},\quad \frac{c+1}{a}

are all integers.

Let T\mathcal{T} be the set of all cyclically divisible ordered triples (a,b,c)(a,b,c) of positive integers. For any positive integer nn, define

S(a,b,c):=a+b+c,S(a,b,c):=a+b+c,

and the arithmetic function F:NNF:\mathbb{N}\to\mathbb{N} by

F(n):={(a,b,c)TS(a,b,c)n}.F(n):=\bigl|\{(a,b,c)\in\mathcal{T}\mid S(a,b,c)\mid n\}\bigr|.

For arithmetic functions u,v:NCu,v:\mathbb{N}\to\mathbb{C}, define their \emph{divisor-sum combination} by

(uv)(n):=dnu(d)v ⁣(nd)(nN),(u * v)(n):=\sum_{d\mid n}u(d)\,v\!\left(\frac{n}{d}\right)\qquad(n\in\mathbb{N}),

and let 1\mathbf{1} denote the constant function 1(n)1\mathbf{1}(n)\equiv 1.

It is known that the set T\mathcal{T} is finite. Moreover, there exists an arithmetic function

G:NZ0,G:\mathbb{N}\to\mathbb{Z}_{\ge 0},

depending only on the values of S(a,b,c)S(a,b,c) for (a,b,c)T(a,b,c)\in\mathcal{T}, such that

F(n)=(G1)(n)=dnG(d)for all nN.F(n) = (G * \mathbf{1})(n) = \sum_{d\mid n} G(d) \quad\text{for all } n\in\mathbb{N}.

Let

N:=107N:=10^7

and define the integer

K:=n=1N(n!)F(n).\mathcal{K} := \prod_{n=1}^{N} \bigl(n!\bigr)^{F(n)}.

Set

E:=v2(K),E := v_2(\mathcal{K}),

the exponent of 22 in the prime factorization of K\mathcal{K}.

Using the above information, determine the exact value of the integer EE.

Ground Truth
91666486036450
Execution Trace
Reasoning Process

[THOUGHT] To solve this problem, we need to determine the exponent of 2 in the prime factorization of (\mathcal{K}), where (\mathcal{K}) is defined as the product of factorials raised to the power of (F(n)) for (n) from 1 to (N = 10^7).

The key steps are:

  1. Understand (F(n)): (F(n)) counts the number of cyclically divisible triples ((a, b, c)) such that (S(a, b, c) = a + b + c) divides (n).
  2. Find (\mathcal{T}): The set of all cyclically divisible triples ((a, b, c)). Since (\mathcal{T}) is finite, we can enumerate all possible triples.
  3. Compute (G): The arithmetic function (G) is defined based on the values of (S(a, b, c)) for ((a, b, c) \in \mathcal{T}).
  4. Compute (F(n)): Using the divisor-sum combination, (F(n) = (G * \mathbf{1})(n) = \sum_{d \mid n} G(d)).
  5. Compute (E): The exponent of 2 in (\mathcal{K}) is the sum over (n) from 1 to (N) of (F(n)) times the exponent of 2 in (n!).

First, we need to find all cyclically divisible triples ((a, b, c)). The conditions are:

  • (\frac{a+1}{b}) is an integer,
  • (\frac{b+1}{c}) is an integer,
  • (\frac{c+1}{a}) is an integer.

We can iterate through possible values of (a, b, c) to find all such triples. Given that (\mathcal{T}) is finite, we can limit the search to reasonable bounds.

Next, for each triple ((a, b, c)), compute (S = a + b + c). The function (G(d)) counts the number of triples with (S = d). Then, (F(n)) is the sum of (G(d)) for all divisors (d) of (n).

Finally, the exponent of 2 in (\mathcal{K}) is: [ E = \sum_{n=1}^{N} F(n) \cdot v_2(n!), ] where (v_2(n!)) is the exponent of 2 in (n!), which can be computed using Legendre's formula: [ v_2(n!) = \sum_{k=1}^{\infty} \left\lfloor \frac{n}{2^k} \right\rfloor. ]

We will implement this step-by-step in Python. [/THOUGHT] [PYTHON] import math from collections import defaultdict

Step 1: Find all cyclically divisible triples (a, b, c)

T = [] max_bound = 100 # Reasonable bound to find all triples

for a in range(1, max_bound + 1): for b in range(1, max_bound + 1): if (a + 1) % b != 0: continue for c in range(1, max_bound + 1): if (b + 1) % c == 0 and (c + 1) % a == 0: T.append((a, b, c))

Step 2: Compute S(a, b, c) for each triple and build G

G = defaultdict(int) for triple in T: S = sum(triple) G[S] += 1

Step 3: Compute F(n) for n from 1 to N

N = 10**7 F = [0] * (N + 1)

for d in G: for multiple in range(d, N + 1, d): F[multiple] += G[d]

Step 4: Compute E = sum_{n=1}^N F(n) * v_2(n!)

def v2_factorial(n): return sum(n // (2k) for k in range(1, int(math.log2(n)) + 2) if 2k <= n)

E = 0 for n in range(1, N + 1): E += F[n] * v2_factorial(n)

print(E) [/PYTHON]

Tool Output
[PYTHON OUTPUT] 91666486036450 [/PYTHON OUTPUT]
Reasoning Process

[THOUGHT] The Python output provides the exact value of (E), the exponent of 2 in the prime factorization of (\mathcal{K}).

[/THOUGHT] \boxed{91666486036450}

Final Model Output
91666486036450

Comparative Analysis (P0) (Average across runs)

Avg Time Taken

Deepseek-R1-distill-Qwen-32B (high)
1136.6
Qwen3-30B-A3B-2507
550.5
Solar-Pro-2 (31B)(high)
382.0
Gemini-3-Pro-Preview
302.1
Deepseek-V3.2
287.0
HCX-007(high)
234.6
Grok-4.1-fast
113.6
GPT-5.1 (high)
109.5
Gemma-3-27B
87.5
GPT-oss-20B (high)
79.3
A.X-4.0 (72B)
56.4
Claude-Opus-4.5
39.1
Llama-VARCO-8B-Instruct
31.3
EXAONE-4.0.1-32B (high)
16.2

Avg Token Usage

Solar-Pro-2 (31B)(high)
146942.0
Gemini-3-Pro-Preview
28923.0
Deepseek-R1-distill-Qwen-32B (high)
24609.7
Grok-4.1-fast
20551.3
Deepseek-V3.2
19976.7
Qwen3-30B-A3B-2507
14717.7
GPT-oss-20B (high)
14426.7
GPT-5.1 (high)
11798.0
Claude-Opus-4.5
11332.7
A.X-4.0 (72B)
8872.0
Llama-VARCO-8B-Instruct
5431.3
EXAONE-4.0.1-32B (high)
5162.7
HCX-007(high)
4787.3
Gemma-3-27B
3081.3