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A071965
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Numbers n such that n = Lpf(n)*Lpf(sigma(n)) where Lpf(x) = A006530(x) is the largest prime factor of x.
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0
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15, 33, 51, 69, 91, 95, 141, 145, 159, 213, 287, 295, 321, 395, 445, 473, 573, 581, 679, 703, 745, 895, 973, 995, 1139, 1149, 1169, 1195, 1199, 1293, 1339, 1345, 1441, 1561, 1717, 1757, 1795, 1891, 1941, 2051, 2147, 2167, 2245, 2353, 2395, 2443, 2495, 2589
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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MATHEMATICA
| Select[Range[2, 3000], FactorInteger[#][[-1, 1]]FactorInteger[ DivisorSigma[ 1, #]] [[-1, 1]]==#&] (* From Harvey P. Dale, Sep 15 2011 *)
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PROG
| (PARI) for(n=1, 3000, if(vecmax(component(factor(n), 1))*vecmax(component(factor(sigma(n)), 1))==n, print1(n, ", ")))
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CROSSREFS
| Sequence in context: A085371 A162887 A190754 * A020184 A108517 A190052
Adjacent sequences: A071962 A071963 A071964 * A071966 A071967 A071968
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KEYWORD
| easy,nonn
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AUTHOR
| Benoit Cloitre (benoit7848c(AT)orange.fr), Jun 16 2002
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