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A068484
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Numbers k that divide phi(k)^2 + sigma(k)^2.
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1
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1, 2, 10, 45, 65, 180, 212, 222, 369, 588, 810, 864, 1274, 1521, 1836, 2548, 2940, 3114, 3552, 4770, 5496, 5684, 6027, 6642, 8820, 9140, 10464, 10614, 13311, 14688, 15210, 20737, 21600, 22776, 26900, 27000, 27270, 28476, 28518, 42212, 42336
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OFFSET
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1,2
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COMMENTS
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LINKS
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MAPLE
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with(numtheory): select(n->modp(phi(n)^2+sigma(n)^2, n)=0, [$1..42500]); # Muniru A Asiru, Oct 16 2018
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MATHEMATICA
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Select[Range[7000], IntegerQ[(EulerPhi[#]^2 + DivisorSigma[1, #]^2)/#] &] (* G. C. Greubel, Oct 15 2018 *)
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PROG
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(GAP) Filtered([1..42500], n->(Phi(n)^2+Sigma(n)^2) mod n=0); # Muniru A Asiru, Oct 16 2018
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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