sum_of_squares_thirteen
plain-language theorem explainer
The equality 13 equals 4 plus 9 holds in the natural numbers. Number theorists checking small cases of sums of two squares would reference this identity. The proof is a one-line term wrapper that invokes native_decide for direct arithmetic verification.
Claim. $13 = 2^2 + 3^2$
background
The module supplies lightweight wrappers around Mathlib arithmetic functions, beginning with the Möbius function μ. This declaration records a basic numerical identity among the file's number-theoretic facts. No upstream results are referenced.
proof idea
The proof is a term-mode one-line wrapper that applies the native_decide tactic to evaluate both sides of the equality by direct computation.
why it matters
This supplies a verified instance of 13 as a sum of two squares inside the number theory layer of the Recognition framework. It supports the module's arithmetic function interfaces, including Möbius-based squarefree checks, though no parent theorems or downstream uses are listed.
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