olymmath

Putnam 2015 B4

  • Session B

Let TT be the set of all triples (a,b,c)(a,b,c) of positive integers for which there exist triangles with side lengths a,b,ca,b,c. Express ∑(a,b,c)∈T2a3b5c\sum_{(a,b,c) \in T} \frac{2^a}{3^b 5^c} as a rational number in lowest terms.

Curated text Kedlaya Putnam archive. Quoted with source.

Solutions

Human solution Solution 1 by Manjul Bhargava, Kiran Kedlaya and Lenny Ng

The terms of the source let olymmath link to this solution but not copy it. Read the solution (Kedlaya Putnam archive).

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