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A063710
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Numbers k such that phi(sigma(k)+k) = sigma(k-phi(k)), where phi is A000010 and sigma is A000203.
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1
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10, 22, 38, 58, 82, 182, 228, 244, 308, 346, 404, 446, 514, 524, 644, 922, 1020, 1214, 1484, 1522, 1538, 1582, 2104, 2408, 5600, 5924, 7596, 8420, 13352, 13378, 13738, 14686, 15012, 20128, 21272, 27084, 27580, 29312, 37158, 43946, 47284, 47468
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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Select[Range[50000], EulerPhi[DivisorSigma[1, #]+#]==DivisorSigma[1, #-EulerPhi[ #]]&] (* Harvey P. Dale, Sep 09 2022 *)
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PROG
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(PARI) s(n) = sigma(n-eulerphi(n)); e(n) = eulerphi(sigma(n)+n); j = []; for(n = 1, 10^5, if(e(n) == s(n), j = concat(j, n))); j
(PARI) { n=0; for (x=2, 10^9, if (eulerphi(sigma(x) + x) == sigma(x - eulerphi(x)), write("b063710.txt", n++, " ", x); if (n==350, break)) ) } \\ Harry J. Smith, Aug 28 2009
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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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