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Number of primes == 5 mod 8 <= n.
0

%I #7 Apr 28 2018 11:49:56

%S 0,0,0,0,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,3,3,3,3,3,3,

%T 3,3,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,6,6,6,6,6,6,6,6,

%U 6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,7,7,7,7,7

%N Number of primes == 5 mod 8 <= n.

%t Accumulate[Table[If[PrimeQ[n]&&Mod[n,8]==5,1,0],{n,110}]] (* _Harvey P. Dale_, Apr 28 2018 *)

%o (PARI) for(n=1,200,print1(sum(i=1,n,if((i*isprime(i)-5)%8,0,1)),","))

%K easy,nonn

%O 1,13

%A _Benoit Cloitre_, Jun 08 2002