A359564 Primitive terms of A359563: terms of A359563 with no proper divisor in A359563.

63, 273, 513, 585, 825, 2107, 2109, 2255, 3069, 3075, 4329, 4697, 4995, 5425, 5673, 6039, 6643, 6935, 6975, 7105, 7161, 8103, 8349, 8541, 8645, 9855, 10235, 11543, 12625, 13725, 13869, 14497, 14841, 16385, 18639, 18915, 19825, 22165, 25025, 26169, 26533, 30225

Offset: 1

Author

Amiram Eldar, Jan 06 2023

Keywords

• nonn

Comments

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

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

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A326835, A359563, A359565, A359566.

Programs

Mathematica

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

PARI

is1(k) = k>1 && k%2 && numdiv(k) > #Set(apply(x->eulerphi(x), divisors(k)));
is(k) = fordiv(k, d, if(is1(d), return(d==k))); return(0);