%I
%S 1,2,3,4,5,6,7,8,9,11,12,13,15,17,18,22,23,24,29,36,37,40,53,55,59,60,
%T 61,62,63,68,69,74,83,86,93,97,107,109,115,116,117,118,123,128,129,
%U 139,142,147,153,154,157,158,162,167,170,175,179,181,182,183,193,194,196
%N Numbers k such that A005728(k) is prime.
%C From a question by Leo Moser.
%D Martin Gardner, "The Last Recreations," Chapter entitled "Strong Laws of Small Primes," Copernicus, SpringerVerlag, NY, 1997, page 199.
%H Amiram Eldar, <a href="/A055201/b055201.txt">Table of n, a(n) for n = 1..10000</a>
%H Leo Moser, <a href="https://books.google.com/books?id=u6N0yfe69RcC&pg=PA312">Problem P42</a>, Canadian Mathematical Bulletin, Vol. 5, No. 3 (1962), pp. 312313.
%t s=1; Do[s = s + EulerPhi[n]; If[PrimeQ[s], Print[n]], {n, 200}]
%Y Cf. A005728.
%Y Complement of A055197.
%K easy,nonn
%O 1,2
%A _Robert G. Wilson v_, Jul 04 2000
