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 A355686 #8 Jul 15 2022 09:54:48
%S A355686 1,-1,-2,-1,-3,3,-2,1,1,3,-4,2,-3,1,8,-1,-5,-5,-4,5,3,3,-6,-7,4,1,-2,
%T A355686 2,-7,-11,-2,3,13,7,8,4,-3,5,8,-5,-5,-1,-4,10,-7,7,-6,8,-1,-4,14,7,-7,
%U A355686 9,18,1,9,7,-8,-16,-3,1,4,-1,13,-17,-4,7,19,-3,-6,16,-5,1,-16,4,9,-7,-6,3,6,3,-8,-5,23,1,20
%N A355686 Dirichlet inverse of A276150, where A276150(n) is the sum of digits when n is written in primorial base.
%H A355686 Antti Karttunen, <a href="/A355686/b355686.txt">Table of n, a(n) for n = 1..30030</a>
%H A355686 <a href="/index/Pri#primorialbase">Index entries for sequences related to primorial base</a>
%F A355686 a(1) = 1, and for n > 1, a(n) = -Sum_{d|n, d<n} A276150(n/d) * a(d).
%F A355686 a(n) = A355687(n) - A276150(n).
%o A355686 (PARI)
%o A355686 A276150(n) = { my(s=0, p=2, d); while(n, d = (n%p); s += d; n = (n-d)/p; p = nextprime(1+p)); (s); };
%o A355686 memoA355686 = Map();
%o A355686 A355686(n) = if(1==n,1,my(v); if(mapisdefined(memoA355686,n,&v), v, v = -sumdiv(n,d,if(d<n,A276150(n/d)*A355686(d),0)); mapput(memoA355686,n,v); (v)));
%Y A355686 Cf. A276150, A355687.
%Y A355686 Cf. also A319715.
%K A355686 sign,base
%O A355686 1,3
%A A355686 _Antti Karttunen_, Jul 14 2022