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A275534
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Number of primes of the form x^2 + y^2 less than or equal to 2*n^2.
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1
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1, 2, 4, 5, 7, 9, 12, 15, 18, 22, 25, 29, 33, 37, 43, 46, 51, 56, 62, 68, 75, 79, 86, 93, 102, 107, 114, 119, 127, 136, 143, 150, 160, 169, 179, 184, 195, 206, 215, 223, 233, 242, 254, 264, 274, 285, 297, 307, 318, 330, 339, 350, 362, 376, 386, 400, 415, 428, 441, 452, 465, 483, 498, 510, 525, 541
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OFFSET
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1,2
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COMMENTS
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LINKS
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MATHEMATICA
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nn = 66; Table[Count[Take[#, PrimePi[2 n^2]], k_ /; k > 0], {n, nn}] &@
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PROG
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(C++)
#include <iostream>
#include <cmath>
using namespace std;
bool IsPrime(int a){
int i = 3;
if(a == 2)
{return true; }
if(a <= 1 || a%2 == 0)
{return false; }
else{
while(i <= sqrt(a)){
if(a%i == 0)
{return false; }
else
{i = i+2; }}
return true; }}
int main(){
int Max, FourKPlusOne;
int limit=25; //Number of terms
for(int TermNum=1; TermNum<=limit; TermNum++){
Max = 2*TermNum*TermNum;
int Term=1;
for(int counter3=1; counter3<=(Max-1)/4; counter3++){
FourKPlusOne=((4*(counter3))+1);
if(IsPrime(FourKPlusOne) == true && FourKPlusOne<=Max)
{Term++; }}
cout<<Term<<endl; }}
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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