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A076375
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Numbers k such that both k and 2*k are balanced numbers (A020492).
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4
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1, 3, 6, 15, 35, 70, 105, 210, 357, 420, 1045, 1485, 2090, 2970, 3135, 3339, 5049, 5940, 6270, 10659, 12441, 12540, 16065, 24871, 24969, 29029, 33915, 35343, 39105, 39585, 49742, 50065, 58058, 58435, 64285, 70686, 71145, 74613, 78210, 87087
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OFFSET
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1,2
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LINKS
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MATHEMATICA
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f[x_] := DivisorSigma[1, x]/EulerPhi[x] Do[s=f[n]; s1=f[2*n]; If[IntegerQ[s]&&IntegerQ[s1], Print[n]], {n, 1, 100000}]
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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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