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Search: id:A088830
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| A088830 |
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a(n)= Min{x : sigma[x]=n.phi[x], x is not a prime}, the least nonprime solutions to sigma[x]=n.phi[x]; special balanced numbers. |
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+0
6
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| 1, 35, 15, 14, 56, 6, 12, 42, 30, 168, 2580, 210, 630, 420, 840, 20790, 416640, 9240, 291060, 83160, 120120, 5165160, 1719277560, 43825320, 26860680, 277560360, 1304863560, 569729160, 587133466920, 16522145640, 33044291280
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OFFSET
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1,2
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FORMULA
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For n > 3, a(n) = A055234(n). - David Wasserman (wasserma(AT)spawar.navy.mil), Aug 18 2005
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MATHEMATICA
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ds[x_, de_] := DivisorSigma[1, x]-de*EulerPhi[x] a[n_] := Block[{m=1, s=ds[m, n]}, While[(s !=0||PrimeQ[m])&&!Greater[m, 100000], m++ ]; m]; Table[a[n], {n, 22}]
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CROSSREFS
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Compare A087979, which has a slightly different definition. Cf. A074891, A000203, A000010, A087979, A020492.
Cf. A055234.
Sequence in context: A034086 A051050 A012862 this_sequence A033355 A022991 A023477
Adjacent sequences: A088827 A088828 A088829 this_sequence A088831 A088832 A088833
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Nov 03 2003
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EXTENSIONS
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More terms from David Wasserman (wasserma(AT)spawar.navy.mil), Aug 18 2005
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