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A275377
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Number of odd prime factors (with multiplicity) of generalized Fermat number 3^(2^n) + 1.
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4
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OFFSET
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0,4
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LINKS
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FORMULA
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EXAMPLE
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b(n) = (3^(2^n) + 1)/2.
Complete Factorizations
b(0) = 2
b(1) = 5
b(2) = 41
b(3) = 17*193
b(4) = 21523361
b(5) = 926510094425921
b(6) = 1716841910146256242328924544641
b(7) = 257*275201*138424618868737*3913786281514524929*P21
b(8) = 12289*8972801*891206124520373602817*P90
b(9) = 134382593*22320686081*12079910333441*100512627347897906177*P93*P101
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PROG
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(PARI) a001222(n) = bigomega(n)
a059919(n) = 3^(2^n)+1
a(n) = if(n==0, 0, a001222(a059919(n))-1) \\ Felix Fröhlich, Jul 25 2016
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CROSSREFS
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KEYWORD
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nonn,hard,more
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AUTHOR
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EXTENSIONS
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a(9) was found in 2008 by Tom Womack
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STATUS
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approved
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