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A071391
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Least number m such that Sigma[m]+Phi[m]=n or 0 if no such number exists.
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2
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0, 1, 0, 2, 0, 3, 0, 0, 4, 5, 0, 0, 0, 6, 0, 0, 0, 0, 8, 0, 0, 10, 0, 0, 0, 13, 0, 0, 0, 14, 0, 12, 0, 17, 0, 0, 0, 19, 16, 0, 0, 0, 0, 21, 18, 22, 0, 0, 0, 20, 25, 0, 0, 26, 0, 0, 0, 27, 0, 0, 0, 31, 0, 0, 0, 0, 0, 24, 0, 34, 0, 35, 0, 37, 0, 0, 0, 38, 32, 30, 0, 41, 0, 0, 0, 43, 0, 0, 0, 0, 0, 0
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,4
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FORMULA
| a(n)=Min{x; A000203(x)+A000010(x)=n} or a(n)=0 if no solution exists.
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EXAMPLE
| n=256: a(256)=110, sigma[110]=216,phi[110]=40, 216+40=256=n.
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MATHEMATICA
| f[x_] := DivisorSigma[1, x]+EulerPhi[x] t=Table[0, {100}]; Do[c=f[n]; If[c<101&&t[[c]]==0, t[[c]]=n], {n, 1, 1000000}]; t
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CROSSREFS
| Cf. A000010, A000203, A065387, A051612, A071391.
Sequence in context: A131104 A141701 A167990 * A102390 A127640 A113303
Adjacent sequences: A071388 A071389 A071390 * A071392 A071393 A071394
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), May 23 2002
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