A269870 Numbers coprime to the number of their odd divisors.
1, 2, 3, 4, 5, 7, 8, 11, 13, 15, 16, 17, 19, 21, 23, 25, 27, 29, 31, 32, 33, 35, 37, 39, 41, 43, 47, 49, 50, 51, 53, 55, 57, 59, 61, 64, 65, 67, 69, 71, 73, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 98, 100, 101, 103, 105, 107, 109, 111, 113, 115, 119, 121, 123, 125, 127, 128, 129, 131, 133, 135, 137, 139, 141, 143, 145, 149, 151, 155
Offset: 1
Keywords
Examples
For n=2, a(2)=2 is a term as the number of odd divisors of 2 is 1, which is coprime to 2.
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000
Crossrefs
Programs
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Mathematica
Select[Range@200, CoprimeQ[#, Length@Select[Divisors[#], OddQ]]&]
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PARI
for(n=1, 200, gcd(n, sumdivmult(n, d, d%2))==1&&print1(n, ", "))
Comments