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%I #11 Dec 15 2017 17:36:12
%S 19,271,919,991,15319,22159,25471,28711,46639,54631,64279,74719,84871,
%T 86311,87679,90199,92431,95239,98479,98911,99559,99991,1125559,
%U 1196911,1338751,1549351,1653679,1688311,1826119,1996759,2064511,2098279
%N Primes whose 10's complement is a square.
%e a(5)=15319 because 100000-15319 = 84681 = 291^2.
%t Select[Prime[Range[160000]],IntegerQ[Sqrt[10^IntegerLength[#]-#]]&] (* _Harvey P. Dale_, May 24 2011 *)
%o (PARI) { PTS(m)=local(ct,sr,ptc); ct=0; sr=0; forprime(p=2,m, ptc=10^length(Str(p))-p; if(issquare(ptc),ct+=1; print1(p","); sr+=1.0/p; )); print(); print("Found "ct" primes < "m); print("Sum of reciprocals = "sr); }
%K nonn,base
%O 1,1
%A _Jason Earls_, May 30 2003
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