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Omni-MATH / Define a number to be an anti-palindrome if, when written in base 3 as a_(n)a_(n−1)…a₀, then a_(i)+a_(n−i)=2 for any 0≤i≤n. Find the number of anti-palindromes less than 3¹² such t…

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problem

Define a number to be an anti-palindrome if, when written in base 3 as anan−1…a0a_{n} a_{n-1} \ldots a_{0}, then ai+an−i=2a_{i}+a_{n-i}=2 for any 0≤i≤n0 \leq i \leq n. Find the number of anti-palindromes less than 3123^{12} such that no two consecutive digits in base 3 are equal.
Plain-text mathematical notation (without MathML)
Define a number to be an anti-palindrome if, when written in base 3 as a_(n)a_(n−1)…a₀, then a_(i)+a_(n−i)=2 for any 0≤i≤n. Find the number of anti-palindromes less than 3¹² such that no two consecutive digits in base 3 are equal.
Original LaTeX notation
Define a number to be an anti-palindrome if, when written in base 3 as $a_{n} a_{n-1} \ldots a_{0}$, then $a_{i}+a_{n-i}=2$ for any $0 \leq i \leq n$. Find the number of anti-palindromes less than $3^{12}$ such that no two consecutive digits in base 3 are equal.

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