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Indian Mathematical Olympiad 1988 - Problem 6

Source:

August 14, 2009
algebrapolynomialmodular arithmeticalgebra proposed

Problem Statement

If a0,a1,,a50 a_0,a_1,\dots,a_{50} are the coefficients of the polynomial \left(1\plus{}x\plus{}x^2\right)^{25} show that a_0\plus{}a_2\plus{}a_4\plus{}\cdots\plus{}a_{50} is even.