A359564 - OEIS

%I #8 Jan 09 2023 01:24:01

%S 63,273,513,585,825,2107,2109,2255,3069,3075,4329,4697,4995,5425,5673,

%T 6039,6643,6935,6975,7105,7161,8103,8349,8541,8645,9855,10235,11543,

%U 12625,13725,13869,14497,14841,16385,18639,18915,19825,22165,25025,26169,26533,30225

%N Primitive terms of A359563: terms of A359563 with no proper divisor in A359563.

%C Odd numbers that are not in A326835 but all of their proper divisors are in it.

%C If k is a term then all the odd multiples of k are terms of A359563.

%H Amiram Eldar, <a href="/A359564/b359564.txt">Table of n, a(n) for n = 1..10000</a>

%t q[n_] := !UnsameQ @@ EulerPhi[Divisors[n]]; primQ[n_] := q[n] && AllTrue[Divisors[n], # == n || !q[#] &]; Select[Range[1, 30000, 2], primQ]

%o (PARI) is1(k) = k>1 && k%2 && numdiv(k) > #Set(apply(x->eulerphi(x), divisors(k)));

%o is(k) = fordiv(k, d, if(is1(d), return(d==k))); return(0);

%Y Cf. A326835, A359563, A359565, A359566.

%K nonn

%O 1,1

%A _Amiram Eldar_, Jan 06 2023