%I A013644
%S A013644 7,14,23,28,32,33,34,47,55,60,62,75,78,79,95,96,98,119,126,128,136,138,
%T A013644 140,141,142,155,167,174,176,180,189,192,194,215,219,220,222,223,248,252,
%U A013644 254,266,287,299,300,305,312,315,318,320,321,322,335,359,368,377,390,392
%N A013644 Numbers n such that continued fraction for sqrt(n) has period 4.
%D A013644 Kenneth H. Rosen, Elementary Number Theory and Its Applications, Addison-Wesley, 
               1984, page 426 (but beware of errors!).
%Y A013644 Sequence in context: A018890 A118502 A036556 this_sequence A050953 A025011 
               A030414
%Y A013644 Adjacent sequences: A013641 A013642 A013643 this_sequence A013645 A013646 
               A013647
%K A013644 nonn
%O A013644 1,1
%A A013644 Clark Kimberling (ck6(AT)evansville.edu)