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Squarefree n such that Q(sqrt(n)) has class number 5.
11

%I #14 May 14 2014 19:01:45

%S 401,439,499,727,817,982,1093,1126,1327,1393,1429,1486,1641,1766,1897,

%T 2027,2081,2153,2399,2878,3121,3134,3181,3238,3251,3253,3814,3967,

%U 3997,4271,4353,4357,4358,4441,4591,4622,4757,4889,5107,5241,5269,5527,5711,5774

%N Squarefree n such that Q(sqrt(n)) has class number 5.

%H Charles R Greathouse IV, <a href="/A029705/b029705.txt">Table of n, a(n) for n = 1..10000</a>

%H <a href="/index/Qua#quadfield">Index entries for sequences related to quadratic fields</a>

%t Select[Range[5774], SquareFreeQ[#] && NumberFieldClassNumber@Sqrt[#] == 5 &] (* _Arkadiusz Wesolowski_, Oct 22 2012 *)

%o (PARI) is(n)=issquarefree(n)&&bnfinit('x^2-n).cyc==[5] \\ _Charles R Greathouse IV_, Oct 18 2012

%Y Cf. A003172, A029702-A029704, A218038-A218042.

%K nonn

%O 1,1

%A Paolo Dominici (pl.dm(AT)libero.it)