A347250 - OEIS

%I #4 Aug 30 2021 09:38:33

%S 9,17,18,34,36,49,67,68,71,72,81,97,98,134,136,142,144,147,162,193,

%T 194,196,268,271,272,283,284,288,291,293,294,324,386,388,392,536,541,

%U 542,544,566,568,576,579,582,586,587,588,647,648,679,772,776,784,961,1072,1082,1084,1087,1088,1132,1136,1151,1152,1158,1163

%N Numbers k for which A331410(k) < A336361(k).

%C If k is a term, then also 2*k is present in this sequence.

%o (PARI)

%o A331410(n) = { my(f=factor(n)); sum(k=1,#f~,if(2==f[k,1],0,f[k,2]*(1+A331410(f[k,1]+1)))); };

%o A336361(n) = if(!bitand(n,n-1),0,1+A336361(sigma(n>>valuation(n,2))));

%o A347249(n) = (A331410(n)-A336361(n));

%o isA347250(n) = (A347249(n)<0);

%Y Cf. A331410, A336361.

%Y Positions of negative terms in A347249.

%K nonn

%O 1,1

%A _Antti Karttunen_, Aug 28 2021