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A062976
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Half-totient function of n is divisible by the number of divisors of n.
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0
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5, 9, 13, 15, 17, 28, 29, 34, 35, 37, 39, 40, 41, 45, 49, 51, 52, 53, 55, 61, 63, 65, 72, 73, 76, 82, 84, 85, 87, 89, 90, 91, 95, 97, 99, 101, 102, 104, 105, 109, 111, 113, 115, 117, 119, 120, 123, 124, 128, 130, 136, 137, 140, 143, 145, 146, 147, 148, 149, 153, 155
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OFFSET
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3,1
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COMMENTS
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Half-totient function is phi(n)/2 for n >= 3, A023022.
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LINKS
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MATHEMATICA
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Select[Range[200], Divisible[EulerPhi[#]/2, DivisorSigma[0, #]]&] (* Harvey P. Dale, Feb 06 2019 *)
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PROG
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(PARI) j=[]; for(n=3, 350, if(Mod(eulerphi(n)/2, numdiv(n))==0, j=concat(j, n))); j
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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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