%I
%S 2,3,5,7,11,17,19,23,29,31,43,47,53,59,67,71,79,83,101,103,107,127,
%T 131,137,139,149,151,163,167,173,179,191,197,199,211,223,227,229,239,
%U 251,257,263,269,271,283,293,307,311,317,331,347,359,367,373,379,383,389
%N Primes p such that there are no other solution to A023900(x) = A023900(p) than a power of p.
%e 2 is a term because there are no other solution to A023900(x) = A023900(2) than other powers of 2.
%o (PARI) f(n) = sumdivmult(n, d, d*moebius(d));
%o isok(p, vp) = {for (k=p+1, p^21, if (f(k) == vp, return (0)); ); return (1); }
%o lista(nn) = {forprime(p=2, nn, vp = f(p); if (isok(p, vp), print1(p, ", ")); ); }
%Y Cf. A023900, A301374.
%Y Complement of A301591.
%K nonn
%O 1,1
%A _Michel Marcus_, Mar 24 2018
