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 A340081 #7 Dec 28 2020 17:47:59 %S A340081 1,1,2,1,4,1,6,1,4,1,10,1,12,1,2,1,16,1,18,1,4,1,22,1,8,1,2,3,28,1,30, %T A340081 1,4,1,2,1,36,1,2,1,40,1,42,1,4,1,46,1,12,1,2,3,52,1,2,1,4,1,58,1,60, %U A340081 1,2,1,16,5,66,1,4,3,70,1,72,1,2,3,4,1,78,1,16,1,82,1,4,1,2,1,88,1,18,1,4,1,2,1,96,1,2,1,100 %N A340081 a(n) = gcd(n-1, A003958(n)). %H A340081 Antti Karttunen, <a href="/A340081/b340081.txt">Table of n, a(n) for n = 1..16384</a> %H A340081 Antti Karttunen, <a href="/A340081/a340081.txt">Data supplement: n, a(n) computed for n = 1..65537</a> %F A340081 a(n) = gcd(n-1, A003958(n)). %F A340081 a(n) = A003958(n) / A340082(n). %F A340081 For n > 1, a(n) = (n-1) / A340083(n). %o A340081 (PARI) %o A340081 A003958(n) = if(1==n,n,my(f=factor(n)); for(i=1,#f~,f[i,1]--); factorback(f)); %o A340081 A340081(n) = gcd(n-1, A003958(n)); %Y A340081 Cf. A003958, A340082, A340083. %Y A340081 Cf. also A049559, A340071. %K A340081 nonn %O A340081 1,3 %A A340081 _Antti Karttunen_, Dec 28 2020