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A325571 Composite numbers n that have no divisor d > 1 such that A048720(A065621(d),n/d) = n. 4

%I #6 May 11 2019 02:24:18

%S 15,25,27,39,51,55,57,63,69,77,81,85,87,91,95,99,111,115,117,119,121,

%T 123,125,141,143,145,147,159,169,171,175,177,183,185,187,201,203,205,

%U 207,209,213,215,219,221,231,235,237,243,245,247,249,253,255,261,265,267,275,285,287,289,291,295,299,301,303,305,319,321

%N Composite numbers n that have no divisor d > 1 such that A048720(A065621(d),n/d) = n.

%H Antti Karttunen, <a href="/A325571/b325571.txt">Table of n, a(n) for n = 1..10000</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 isA325571(n) = ((n>1)&&!isprime(n)&&fordiv(n,d,if(A048720(A065621(n/d),d)==n,return(d==n))));

%Y Cf. A048720, A065621, A325573.

%Y Intersection of A002808 and A325570.

%K nonn

%O 1,1

%A _Antti Karttunen_, May 10 2019

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Last modified April 17 07:50 EDT 2024. Contains 371756 sequences. (Running on oeis4.)