This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A269870 #14 Dec 02 2019 04:11:42 %S A269870 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, %T A269870 43,47,49,50,51,53,55,57,59,61,64,65,67,69,71,73,77,79,81,83,85,87,89, %U A269870 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 %N A269870 Numbers coprime to the number of their odd divisors. %C A269870 Contains A046642. %C A269870 Conjecture: the asymptotic density of this sequence is the same as that of A046642. %H A269870 Amiram Eldar, <a href="/A269870/b269870.txt">Table of n, a(n) for n = 1..10000</a> %e A269870 For n=2, a(2)=2 is a term as the number of odd divisors of 2 is 1, which is coprime to 2. %t A269870 Select[Range@200, CoprimeQ[#, Length@Select[Divisors[#], OddQ]]&] %o A269870 (PARI) for(n=1, 200, gcd(n, sumdivmult(n, d, d%2))==1&&print1(n, ", ")) %Y A269870 Cf. A001227 (number of odd divisors), A046642 (numbers coprime to the number of their divisors), A269818 (counterpart for the number of even divisors). %K A269870 nonn %O A269870 1,2 %A A269870 _Waldemar Puszkarz_, Mar 06 2016