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Search: id:A083538
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| 3, 12, 28, 42, 2, 6, 120, 195, 234, 6, 21, 2, 84, 1, 744, 558, 78, 780, 210, 336, 72, 6, 10, 1860, 1302, 420, 35, 420, 60, 36, 2016, 336, 72, 72, 4368, 3458, 570, 210, 1260, 105, 112, 264, 231, 182, 156, 6, 372, 7068, 589, 744, 1764, 1323, 180, 15, 15, 6, 72, 6, 70
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OFFSET
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1,1
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FORMULA
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a(n) = LCM[phi[n+1], phi[n]]/GCD[phi[n+1], phi[n]] = (phi[n+1].phi[n])/GCD[phi[n+1], phi[n]]^2 = A083542(n)/A060780(n)^2.
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EXAMPLE
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n=10: sigma[10]=18, sigma[11]=12, lcm[18, 12]=36, gcd[18, 12]=6, a(10)=36/6=6.
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MATHEMATICA
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f[x_] := DivisorSigma[1, x] t=Table[LCM[f[w+1], f[w]]/GCD[f[w+1], f[w]], {w, 1, 128}]
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CROSSREFS
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Cf. A000010, A066813, A058515.
Cf. A000203, A060781, A060780, A083539.
Sequence in context: A133647 A009222 A083543 this_sequence A060781 A083539 A066643
Adjacent sequences: A083535 A083536 A083537 this_sequence A083539 A083540 A083541
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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), May 21 2003
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EXTENSIONS
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Edited by njas, Apr 29 2007
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