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 A330944 #10 Nov 03 2023 11:21:55
%S A330944 0,1,0,2,0,1,1,3,0,1,0,2,1,2,0,4,0,1,1,2,1,1,1,3,0,2,0,3,1,1,0,5,0,1,
%T A330944 1,2,1,2,1,3,0,2,1,2,0,2,1,4,2,1,0,3,1,1,0,4,1,2,0,2,1,1,1,6,1,1,0,2,
%U A330944 1,2,1,3,1,2,0,3,1,2,1,4,0,1,0,3,0,2,1
%N A330944 Number of nonprime prime indices of n.
%C A330944 A prime index of n is a number m such that prime(m) divides n. The multiset of prime indices of n is row n of A112798.
%F A330944 a(n) + A257994(n) = A001222(n).
%F A330944 Additive with a(p^e) = e if primepi(p) is nonprime, and 0 otherwise. - _Amiram Eldar_, Nov 03 2023
%e A330944 24 has prime indices {1,1,1,2}, of which {1,1,1} are nonprime, so a(24) = 3.
%t A330944 Table[Total[Cases[If[n==1,{},FactorInteger[n]],{p_,k_}/;!PrimeQ[PrimePi[p]]:>k]],{n,30}]
%o A330944 (PARI) a(n) = my(f=factor(n)); sum(k=1, #f~, if(!isprime(primepi(f[k,1])), f[k,2], 0)); \\ _Daniel Suteu_, Jan 14 2020
%Y A330944 The number of prime prime indices is given by A257994.
%Y A330944 Primes of prime index are A006450.
%Y A330944 Primes of nonprime index are A007821.
%Y A330944 Products of primes of prime index are A076610.
%Y A330944 Products of primes of nonprime index are A320628.
%Y A330944 Numbers whose prime indices are not all prime are A330945.
%Y A330944 Cf. A000040, A000720, A001222, A007097, A018252, A056239, A112798, A302242, A320629, A320633, A330946, A330947.
%K A330944 nonn,easy
%O A330944 1,4
%A A330944 _Gus Wiseman_, Jan 13 2020