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 A318979 #16 Dec 06 2021 03:06:49
%S A318979 0,1,0,2,0,2,0,3,0,2,0,4,0,2,1,4,0,3,0,4,0,2,0,6,0,2,0,4,0,5,0,5,1,2,
%T A318979 1,6,0,2,0,6,0,4,0,4,2,2,0,8,0,3,1,4,0,4,1,6,0,2,0,9,0,2,0,6,0,5,0,4,
%U A318979 1,5,0,9,0,2,2,4,1,4,0,8,0,2,0,8,1,2,0
%N A318979 Number of divisors of n with relatively prime prime indices, meaning they belong to A289509.
%C A318979 A prime index of n is a number m such that prime(m) divides n.
%H A318979 Antti Karttunen, <a href="/A318979/b318979.txt">Table of n, a(n) for n = 1..20000</a>
%H A318979 <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a>
%F A318979 a(n) = A000005(n) - A327657(n). - _Antti Karttunen_, Dec 05 2021
%e A318979 The divisors of 36 are 1, 2, 3, 4, 6, 9, 12, 18, 36, corresponding to the prime index multisets (), (1), (2), (11), (12), (22), (112), (122), (1122) respectively. Of these, only (1), (11), (12), (112), (122), (1122) are relatively prime, corresponding to the divisors 2, 4, 6, 12, 18, 36, so a(36) = 6.
%t A318979 Table[Length[Select[Divisors[n],GCD@@PrimePi/@FactorInteger[#][[All,1]]==1&]],{n,100}]
%o A318979 (PARI) a(n) = sumdiv(n, d, gcd(apply(x->primepi(x), factor(d)[,1])) == 1); \\ _Michel Marcus_, Jan 09 2019
%Y A318979 Cf. A000005, A000837, A001221, A018783, A056239, A289508, A289509, A296150, A298748, A318978, A327657.
%K A318979 nonn
%O A318979 1,4
%A A318979 _Gus Wiseman_, Sep 06 2018