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A078558
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GCD of sigma(p#) and phi(p#) where p# = A002110(n) is the product of the first n primes.
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4
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1, 2, 8, 48, 96, 1152, 9216, 1658880, 3317760, 92897280, 2786918400, 100329062400, 802632499200, 370816214630400, 741632429260800, 2966529717043200, 29665297170432000, 355983566045184000
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OFFSET
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1,2
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LINKS
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FORMULA
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EXAMPLE
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m=2,3,30,210 primorials are balanced numbers so these GCD() equals phi(): a(n)=1,2,8,48 (see A005867).
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MATHEMATICA
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GCD[DivisorSigma[1, #], EulerPhi[#]]&/@FoldList[Times, Prime[Range[20]]] (* Harvey P. Dale, Feb 28 2016 *)
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PROG
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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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