login
a(n) is the largest divisor d of n such that A048720(A065621(d),n/d) = n.
7

%I #7 May 11 2019 02:23:45

%S 1,2,1,4,1,2,1,8,3,2,1,4,1,2,1,16,1,6,1,4,3,2,1,8,1,2,1,4,1,2,1,32,11,

%T 2,5,12,1,2,1,8,1,6,1,4,3,2,1,16,7,2,1,4,1,2,1,8,1,2,1,4,1,2,1,64,13,

%U 22,1,4,1,10,1,24,1,2,5,4,1,2,1,16,1,2,1,12,1,2,1,8,1,6,1,4,3,2,1,32,1,14,1,4,1,2,1,8,7

%N a(n) is the largest divisor d of n such that A048720(A065621(d),n/d) = n.

%H Antti Karttunen, <a href="/A325566/b325566.txt">Table of n, a(n) for n = 1..16383</a>

%H Antti Karttunen, <a href="/A325566/a325566.txt">Data supplement: n, a(n) computed for n = 1..65537</a>

%o (PARI)

%o A048720(b,c) = fromdigits(Vec(Pol(binary(b))*Pol(binary(c)))%2, 2);

%o A065621(n) = bitxor(n-1,n+n-1);

%o A325566(n) = fordiv(n,d,if(A048720(A065621(n/d),d)==n,return(n/d)));

%Y Cf. A048720, A065621, A325565, A325567, A325570 (positions of ones).

%K nonn

%O 1,2

%A _Antti Karttunen_, May 09 2019