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 A275534 Number of primes of the form x^2 + y^2 less than or equal to 2*n^2. 1
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Number of terms in A002313 that are less than A001105(n). LINKS William Boyles, Table of n, a(n) for n = 1..1000 MATHEMATICA nn = 66; Table[Count[Take[#, PrimePi[2 n^2]], k_ /; k > 0], {n, nn}] &@ SquaresR[2, Prime@ Range@ PrimePi[2 nn^2]] (* Michael De Vlieger, Aug 01 2016 *) PROG (C++) #include #include 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<

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Last modified January 21 17:07 EST 2019. Contains 319350 sequences. (Running on oeis4.)