A054021 Numbers n such that Chowla's function of n is divisible by the number of proper divisors of n.
2, 3, 4, 5, 7, 8, 11, 12, 13, 14, 17, 18, 19, 23, 24, 26, 27, 29, 31, 32, 35, 37, 38, 40, 41, 43, 47, 52, 53, 56, 59, 61, 62, 63, 65, 66, 67, 71, 73, 74, 77, 79, 83, 86, 88, 89, 90, 92, 95, 97, 101, 103, 104, 107, 109, 110, 112, 113, 119, 122, 125, 127, 128, 131, 134, 136
Offset: 1
Keywords
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000
Programs
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Maple
with(numtheory): [seq(`if`((sigma(i)-i-1) mod (tau(i)-1)=0,i,print( )),i=2..1000)];
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Mathematica
Select[Range[2,150],Divisible[DivisorSigma[1,#]-1-#,DivisorSigma[ 0,#]-1]&] (* Harvey P. Dale, Aug 13 2018 *)
Comments