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Primes that becomes a square when prefixed with a 3.
8

%I #15 Jun 24 2016 04:52:17

%S 61,4969,6481,9601,23761,26041,37561,68449,88129,129361,179089,214849,

%T 265249,301489,308761,411409,455881,463321,485689,508129,523129,

%U 530641,659569,713329,751969,829849,916441,924361,948169,964081,996001,1058329,1147561,1281649

%N Primes that becomes a square when prefixed with a 3.

%H Vincenzo Librandi, <a href="/A167736/b167736.txt">Table of n, a(n) for n = 1..107</a>

%t Select[Prime[Range[1000000]],IntegerQ[Sqrt[FromDigits[Join[{3}, IntegerDigits[ #]]]]]&] (* _Harvey P. Dale_, Nov 01 2011 *)

%o (PARI)

%o \\ terms upto 10^n

%o upto(n) = {my(sqrt31 = sqrt(3.1), sqrt40 = sqrt(4.0), r); for(k=2, n, for(j = ceil((sqrt31 * sqrt(10^k))), floor(sqrt40 * sqrt(10^k)), r = j^2%10^k; if(isprime(r), print1(r", "))))} \\ David A. Corneth, Jun 24 2016

%Y Cf. A167734, A167735, A167737, A167738, A167739, A167740, A167741.

%K base,nonn

%O 1,1

%A _Claudio Meller_, Nov 10 2009

%E More terms from _Harvey P. Dale_, Nov 01 2011