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A117856
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Number of palindromes of length n (in base 4).
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1
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3, 3, 12, 12, 48, 48, 192, 192, 768, 768, 3072, 3072, 12288, 12288, 49152, 49152, 196608, 196608, 786432, 786432, 3145728, 3145728, 12582912, 12582912, 50331648, 50331648, 201326592, 201326592, 805306368, 805306368, 3221225472, 3221225472, 12884901888
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OFFSET
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1,1
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LINKS
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FORMULA
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a(n) = 3*4^floor((n-1)/2)).
a(n) = 4*a(n-2). G.f. -3*x*(x+1) / ((2*x-1)*(2*x+1)). [Colin Barker, Feb 15 2013]
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MATHEMATICA
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CROSSREFS
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KEYWORD
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nonn,base,easy,changed
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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