A090777 Numbers k such that sigma(k) divides k^2.
1, 6, 28, 120, 364, 496, 672, 840, 1080, 1488, 1782, 2280, 3276, 3472, 7440, 8128, 8736, 11880, 12400, 18360, 20832, 24384, 25296, 26208, 30240, 30256, 32760, 35640, 37200, 56896, 57240, 84360, 86800, 90768, 115560, 121920, 131040, 149856, 170688
Offset: 1
Keywords
Links
- Donovan Johnson, Table of n, a(n) for n = 1..1000
Programs
-
Mathematica
Select[Range[200000], Divisible[#^2, DivisorSigma[1, #]] &] (* Amiram Eldar, May 09 2022 *)
-
PARI
for (n=1,10^6, if ( n^2 % sigma(n) ==0, print1(n,", "))); /* Joerg Arndt, May 28 2012 */