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Squares that becomes primes when prefixed with a 3.
1

%I #13 Oct 14 2017 14:55:47

%S 1,49,121,169,361,529,1849,2401,3721,6241,8281,9409,11881,14161,14641,

%T 19321,20449,25921,27889,39601,49729,51529,52441,69169,76729,83521,

%U 89401,94249,104329,113569,124609,143641,165649,175561,187489,190969

%N Squares that becomes primes when prefixed with a 3.

%H G. C. Greubel, <a href="/A167718/b167718.txt">Table of n, a(n) for n = 1..10000</a>

%t Select[Range[1, 4000, 2]^2, PrimeQ[FromDigits[Join[{3}, IntegerDigits[#]]]] &] (* _G. C. Greubel_, Jun 21 2016 *)

%K base,nonn

%O 1,2

%A _Claudio Meller_, Nov 10 2009

%E Definition modified by _Harvey P. Dale_, Oct 14 2017