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A229767
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Largest prime factor of 2^(2*n+1)-2^(n+1)+1.
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4
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5, 5, 113, 37, 397, 1613, 61, 953, 457, 14449, 30269, 8101, 246241, 107367629, 384773, 312709, 47392381, 184481113, 1249, 12112549, 1759217765581, 54001, 140737471578113, 4981857697937, 26317, 1801439824104653, 415878438361, 525313, 174877, 368140581013
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OFFSET
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1,1
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COMMENTS
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2^(2*n+1)-2^(n+1)+1 is a factor of 4^(2*n+1)+1.
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LINKS
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EXAMPLE
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For n=5, 2^(2*n+1)-2^(n+1)+1 = 1985 = 5*397, so a(5)=397.
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PROG
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(PARI) a(n) = {f=factor(2^(2*n+1)-2^(n+1)+1); f[matsize(f)[1], 1]}
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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