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Sierpiński numbers that are squares.
1

%I #13 Mar 29 2016 22:39:45

%S 18213931681,5044241991721,6093734165401,6278567569849,17919144076201,

%T 52536446729209,56470430531761,72659547739249,107737943736721,

%U 123343213788001,136925780937841,170306127919321,211292941174561,296693149397089,321058916825689

%N Sierpiński numbers that are squares.

%C This sequence contains infinitely many numbers that end in 5. See also A233469.

%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Sierpinski_number">Sierpinski number</a>

%F A000290 INTERSECT A076336.

%F a(n) = A270896(n)^2.

%Y Cf. A076336, A233469, A270896.

%K nonn,hard

%O 1,1

%A _Arkadiusz Wesolowski_, Mar 25 2016