Search: id:A062325
Results 1-1 of 1 results found.

%I A062325
%S A062325 1,3,7,12,26,45,55,79,106,123,211,252,422,446,595,723,907,1019,1101,
%T A062325 1448,1595,1687,1797,1849,1949,2058,2393,2516,2703,2819,3146,3339,3477,
%U A062325 3626,4353,4437,4590,5153,5398,5653,5836,6276,6543,6736,6911,7207,7695
%N A062325 n for which phi(prime(n)) is a perfect square.
%C A062325 Also A002496 indexed by A000040.
%H A062325 Harry J. Smith, <a href="b062325.txt">Table of n, a(n) for n=1,...,1000</
               a>
%F A062325 A062325(n) = A000720[A002496(n)] A000040[A062325(n)] = A002496(n) Sqrt[A062325(n)-1] 
               = A005574(n)
%e A062325 a(8)=79 because the 79th prime is 401 and phi(401) is 400 = 20^2. a(15)=595 
               because the 595th prime is 4357 and phi(4357) is 4356 = 66^2.
%t A062325 Flatten[Position[Table[IntegerQ[Sqrt[Prime[w]-1]], {w, 1, 25000}], True]]
%o A062325 (PARI) for(n=1,1600, if(issquare(eulerphi(prime(n))),print(n)))
%o A062325 (PARI) { default(primelimit, 2*10^8); n=m=0; forprime (p=2, 2*10^8, m++; 
               if (issquare(eulerphi(p)), write("b062325.txt", n++, " ", m); if 
               (n==1000, break)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), 
               Aug 05 2009]
%Y A062325 Cf. A000040, A000720, A001912, A002496, A005574, A062325, A090693.
%Y A062325 Sequence in context: A029452 A034434 A167491 this_sequence A099811 A063072 
               A007626
%Y A062325 Adjacent sequences: A062322 A062323 A062324 this_sequence A062326 A062327 
               A062328
%K A062325 easy,nonn
%O A062325 1,2
%A A062325 Jason Earls (zevi_35711(AT)yahoo.com), Jul 05 2001
%E A062325 More terms from Labos E. (labos(AT)ana.sote.hu), Jul 09 2001

Search completed in 0.002 seconds