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%I #11 May 21 2023 11:46:54
%S 9,81,441,729,1089,1521,6561,8649,16641,19881,33489,53361,56169,71289,
%T 74529,84681,88209,103041,168921,173889,251001,257049,263169,269361,
%U 288369,301401,314721,335241,370881,423801,463761,514089,549081,558009
%N Squares that become a prime number when prefixed with a 2.
%C Subsequence of squares of A032665. - _Michel Marcus_, Jun 21 2016
%H G. C. Greubel, <a href="/A167717/b167717.txt">Table of n, a(n) for n = 1..10000</a>
%t Select[Range[1, 500, 2]^2, PrimeQ[FromDigits[Join[{2}, IntegerDigits[#]]]] &](* _G. C. Greubel_, Jun 21 2016 *)
%t Select[Range[800]^2,PrimeQ[2*10^IntegerLength[#]+#]&] (* _Harvey P. Dale_, Oct 23 2022 *)
%Y Cf. A032665.
%K base,nonn
%O 1,1
%A _Claudio Meller_, Nov 10 2009
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