A356410 Numbers k for which k^3 is divisible by sigma(k).
1, 6, 28, 30, 84, 102, 120, 364, 420, 496, 672, 840, 1080, 1092, 1320, 1428, 1488, 1782, 2280, 2716, 2760, 3276, 3360, 3444, 3472, 3480, 3720, 4452, 5640, 7080, 7392, 7440, 7560, 8128, 8148, 8736, 8910, 9240, 9480, 10416, 10920, 11880, 12400, 15456, 15960
Offset: 1
Keywords
Examples
30 is a term, because 30^3 = 27000, sigma(30) = 72 and 27000 / 72 = 375.
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..2000 from Robert Israel)
Programs
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Maple
select(t -> t^3 mod numtheory:-sigma(t) = 0, [$1..20000]); # Robert Israel, Sep 16 2022
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Mathematica
Select[Range[16000], Divisible[#^3, DivisorSigma[1, #]] &] Select[Range[16000],PowerMod[#,3,DivisorSigma[1,#]]==0&] (* Harvey P. Dale, Sep 04 2024 *)
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PARI
for(k=1,10^6,if(k^3%sigma(k)==0,print1(k,", "))) \\ Alexandru Petrescu, Sep 10 2022