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A073757
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a(n) = d(n) + phi(n) - 1.
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24
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1, 2, 3, 4, 5, 5, 7, 7, 8, 7, 11, 9, 13, 9, 11, 12, 17, 11, 19, 13, 15, 13, 23, 15, 22, 15, 21, 17, 29, 15, 31, 21, 23, 19, 27, 20, 37, 21, 27, 23, 41, 19, 43, 25, 29, 25, 47, 25, 44, 25, 35, 29, 53, 25, 43, 31, 39, 31, 59, 27, 61, 33, 41, 38, 51, 27, 67, 37, 47, 31, 71, 35, 73
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OFFSET
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1,2
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COMMENTS
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Old name was: Number of numbers "related" to n: either divisors or terms in RRS of n.
RRS of n means reduced residue system modulo n. One considers here the smallest positive one. - Wolfdieter Lang, Jan 16 2016
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LINKS
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FORMULA
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If p is prime then a(p) = p.
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MATHEMATICA
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DivisorSigma[0, #] + EulerPhi[#] - 1 & /@ Range[73] (* Jayanta Basu, Jul 09 2013 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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