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Search: id:A070017
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| A070017 |
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Least numbers m such that GCD of two consecutive values of cototients, i.e. GCD[cototient[m+1],cototient[m]] equals 2n-1. |
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+0
1
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| 2, 9, 38, 392, 135, 120, 362, 116, 745, 1183, 294, 528, 1395, 428, 1378, 2602, 1185, 203, 2313, 3042, 1966, 3549, 1431, 551, 7838, 4076, 473, 2635, 903, 2044, 13178, 942, 6819, 12418, 1188, 2264, 3282, 1775, 1517, 2127, 24380, 2884, 2035, 11481
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OFFSET
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1,1
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FORMULA
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a(n)=Min{x; A049586(x)=2n-1}
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EXAMPLE
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n=104:2n-1=207,a(104)=235148 because A049586(235148)=207 and it is the smallest such a number. Remark that Count[t=Table[f[w],{w,1,100000}],1]=83132. This suggests that majority of values in A049586 equals one.
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MATHEMATICA
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f[x_] := GCD[x-EulerPhi[x], (x+1)-EulerPhi[x+1]] t = Table[0, {256} ]; Do[ c = f[n]; If[c <257 && t[[c]] == 0, t[[c]] = n], {n, 2, 10} ]; t
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CROSSREFS
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Sequence in context: A057647 A069724 A132961 this_sequence A054129 A037737 A037632
Adjacent sequences: A070014 A070015 A070016 this_sequence A070018 A070019 A070020
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KEYWORD
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nonn
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AUTHOR
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Labos E. and Benoit Cloitre (benoit7848c(AT)orange.fr) (labos(AT)ana.sote.hu), Apr 12 2002
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