OFFSET
1,1
COMMENTS
Numbers k such that k and k+2 are both in A359563.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
MATHEMATICA
q[n_] := q[n] = UnsameQ @@ EulerPhi[Divisors[n]]; Select[Range[1, 10^6, 2], ! q[#] && ! q[# + 2] &]
PROG
(PARI) is(k) = k>1 && k%2 && numdiv(k) > #Set(apply(x->eulerphi(x), divisors(k)));
lista(kmax) = {my(q1 = 0, q2); forstep(k = 3, kmax, 2, q2 = is(k); if(q1 && q2, print1(k-2, ", ")); q1 = q2); }
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Jun 08 2024
STATUS
approved