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 A359589 #16 Jan 11 2023 15:58:56 %S A359589 1,0,0,0,0,-4,0,-2,-5,0,0,0,0,-2,-1,0,0,0,0,-2,-9,0,0,0,-9,-14,-2,0,0, %T A359589 0,0,0,-13,0,-5,12,0,-20,-1,0,0,0,0,-2,-2,-24,0,10,-13,-14,-9,-6,0,40, %U A359589 -1,0,-1,0,0,0,0,-2,-2,2,-17,0,0,-2,-1,0,0,20,0,-2,-4,-4,-17,0,0,0,20,0,0,16,-1,-14,-1,-34 %N A359589 Dirichlet inverse of function f(n) = (-1 + gcd(A003415(n), A276086(n))), where A003415 is the arithmetic derivative and A276086 is the primorial base exp-function. %H A359589 Antti Karttunen, <a href="/A359589/b359589.txt">Table of n, a(n) for n = 1..30030</a> %F A359589 a(1) = 1, and for n > 1, a(n) = -Sum_{d|n, d<n} (A327858(n/d)-1) * a(d). %F A359589 a(n) == A358777(n) mod 2. %o A359589 (PARI) %o A359589 A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1])); %o A359589 A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); }; %o A359589 A327858(n) = gcd(A003415(n), A276086(n)); %o A359589 memoA359589 = Map(); %o A359589 A359589(n) = if(1==n,1,my(v); if(mapisdefined(memoA359589,n,&v), v, v = -sumdiv(n,d,if(d<n,(A327858(n/d)-1)*A359589(d),0)); mapput(memoA359589,n,v); (v))); %Y A359589 Cf. A003415, A276086, A327858, A359595 (parity of terms), A359596 (positions of odd terms). %Y A359589 Agrees paritywise with A358777. %Y A359589 Cf. also A346242, A354347, A354348, A359603. %K A359589 sign %O A359589 1,6 %A A359589 _Antti Karttunen_, Jan 09 2023