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2, 14, 3, 170, 3570, 592922491, 17194752239, 498892319051, 14467877252479, 421652049419104, 12227909433154016, 377536703748630244, 926952707565364023467, 1485824943636552705389704010031591742370238670767627108613, 18031470774665264926975299618474551942701594055200456829621877, 219559123426400144842876467461078524942414020727022446946702813568
(list;
graph;
refs;
listen;
history;
text;
internal format)
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OFFSET
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1,1
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COMMENTS
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10^70 < a(17) <= 842075173279428103504117746722346581987825143261978794674517195307859044272000. - Max Alekseyev, Oct 07 2023
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LINKS
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EXAMPLE
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MATHEMATICA
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a[n_] := Module[{k=2}, While[!IntegerQ[Surd[DivisorSigma[1, k]*EulerPhi[k], n]], k++]; k]; Array[a, 1, 5]
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PROG
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(PARI) a(n) = {my(k=2); while (!ispower(sigma(k)*eulerphi(k), n), k++); k; } \\ Michel Marcus, Mar 06 2019
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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