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 A324878 #10 Mar 19 2019 23:01:30 %S A324878 0,0,0,1,0,1,0,0,6,0,0,1,0,1,8,8,0,6,0,0,16,1,0,0,0,1,12,1,0,8,0,8,0, %T A324878 1,20,8,0,1,66,0,0,17,0,1,8,1,0,8,0,0,2,1,0,12,36,0,258,1,0,0,0,1,16, %U A324878 40,0,1,0,1,0,20,0,24,0,1,24,1,32,67,0,8,0,1,0,1,132,1,1026,0,0,40,72,1,0,1,256,16,0,1,68,16,0,3,0,0,46 %N A324878 Xor-Moebius transform of A324398, where A324398(n) = A156552(n) AND (A323243(n) - A156552(n)). %H A324878 Antti Karttunen, <a href="/A324878/b324878.txt">Table of n, a(n) for n = 1..10000</a> (based on Hans Havermann's factorization of A156552) %H A324878 <a href="/index/Bi#binary">Index entries for sequences related to binary expansion of n</a> %H A324878 <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a> %H A324878 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a> %F A324878 a(p) = 0 for all primes p. %o A324878 (PARI) %o A324878 A156552(n) = {my(f = factor(n), p2 = 1, res = 0); for(i = 1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p * p2 * (2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); res}; \\ From A156552 %o A324878 A318458(n) = bitand(n, sigma(n)-n); %o A324878 A324398(n) = if(1==n,0,A318458(A156552(n))); %o A324878 \\ Or, equivalently: %o A324878 A324398(n) = { my(k=A156552(n)); bitand(k,(A323243(n)-k)); }; \\ Needs also code from A323243. %o A324878 A324878(n) = { my(v=0); fordiv(n, d, if(issquarefree(n/d), v=bitxor(v, A324398(d)))); (v); }; %Y A324878 Cf. A156552, A318458, A324820, A324821, A324876, A324877. %K A324878 nonn %O A324878 1,9 %A A324878 _Antti Karttunen_, Mar 18 2019