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A067799
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Numbers k such that phi(k) + phi(k+1) = sigma(k).
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1
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2, 3, 5, 115, 143, 287, 371, 413, 623, 791, 4067, 10031, 24149, 32335, 39689, 88403, 93443, 107365, 148735, 168833, 212993, 427763, 555947, 650095, 925253, 1017821, 1117457, 1139467, 1229327, 1270801, 1407295, 2184221, 2294509, 2913757, 3258355, 4699981, 5747291
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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[10^6], EulerPhi[#] + EulerPhi[# + 1] == DivisorSigma[1, #] &] (* Amiram Eldar, May 21 2022 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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