A325640 - OEIS

%I #9 May 21 2019 22:03:46

%S 1,1,1,1,1,6,1,1,1,2,1,4,1,2,3,1,1,3,1,2,1,2,1,12,1,2,1,28,1,6,1,1,3,

%T 2,1,1,1,2,1,10,1,2,1,4,3,2,1,4,1,1,3,2,1,6,1,8,1,2,1,12,1,2,1,1,1,6,

%U 1,2,1,2,1,3,1,2,1,4,1,6,1,2,1,2,1,28,1,2,1,4,1,18,1,4,1,2,5,12,1,1,3,1,1,6,1,2,3

%N a(n) = A091255(n, A009194(n)) = A091255(n, gcd(n, sigma(n))).

%H Antti Karttunen, <a href="/A325640/b325640.txt">Table of n, a(n) for n = 1..65537</a>

%H <a href="/index/Ge#GF2X">Index entries for sequences related to polynomials in ring GF(2)[X]</a>

%H <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>

%F a(n) = A091255(n, A009194(n)) = A091255(n, gcd(n, sigma(n))).

%o (PARI)

%o A009194(n) = gcd(n,sigma(n));

%o A091255sq(a,b) = fromdigits(Vec(lift(gcd(Pol(binary(a))*Mod(1, 2),Pol(binary(b))*Mod(1, 2)))),2);

%o A325640(n) = A091255sq(n, A009194(n));

%Y Cf. A000203, A007691 (fixed points), A009194, A091255, A325634.

%Y Differs from A325632 and A325633 for the first time at n=45, where a(45) = 3, while A325632(45) = 5 and A325633(45) = 1.

%K nonn

%O 1,6

%A _Antti Karttunen_, May 21 2019