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Search: id:A087271
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| A087271 |
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Least number x such that GCD[x,pi[x]]=n. |
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+0
1
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| 1, 4, 6, 8, 50, 66, 77, 56, 27, 30, 33, 156, 169, 182, 465, 224, 238, 252, 2299, 1380, 189, 902, 207, 96, 100, 1872, 1323, 2464, 1247, 120, 1333, 3168, 528, 1258, 1295, 828, 3441, 2888, 1755, 5800, 1271, 1932, 731, 748, 765, 2852, 2209, 11568, 2695, 4000
(list; graph; listen)
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OFFSET
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1,2
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FORMULA
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a(n)=Min{x; GCD[x, A000720(x)]=n}
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EXAMPLE
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n=253: a(253)=91586, pi(91586)=8855,
GCD[91586,8855]=253 first time.
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MATHEMATICA
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f[x_] := GCD[x, PrimePi[x]]; t=Table[0, {257}]; Do[s=f[n]; If[s<258&&t[[s]]==0, t[[s]]=n], {n, 1, 100000}]; t
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CROSSREFS
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Cf. A007053, A000720, A087266-A087269, A057809.
Adjacent sequences: A087268 A087269 A087270 this_sequence A087272 A087273 A087274
Sequence in context: A137026 A028987 A090938 this_sequence A067797 A013285 A013289
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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), Sep 16 2003
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