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A066490 Number of primes of the form 4m+3 <= n. 5

%I

%S 0,0,1,1,1,1,2,2,2,2,3,3,3,3,3,3,3,3,4,4,4,4,5,5,5,5,5,5,5,5,6,6,6,6,

%T 6,6,6,6,6,6,6,6,7,7,7,7,8,8,8,8,8,8,8,8,8,8,8,8,9,9,9,9,9,9,9,9,10,

%U 10,10,10,11,11,11,11,11,11,11,11,12,12,12,12,13,13,13,13,13,13,13,13,13

%N Number of primes of the form 4m+3 <= n.

%C Partial sums of A079261. - _Reinhard Zumkeller_, Feb 06 2014

%H T. D. Noe, <a href="/A066490/b066490.txt">Table of n, a(n) for n=1..10000</a>

%t Table[ Length[ Select[ Union[ Table[ Prime[ PrimePi[i]], {i, 2, n}]], Mod[ #, 4] == 3 & ]], {n, 2, 100} ]

%o (PARI) for(n=1,100,print1(sum(i=1,n,if((i*isprime(i)-3)%4,0,1)),","))

%o (Haskell)

%o a066490 n = a066490_list !! (n-1)

%o a066490_list = scanl1 (+) $ map a079261 [1..]

%o -- _Reinhard Zumkeller_, Feb 06 2014

%Y Cf. A066339.

%K easy,nonn

%O 1,7

%A _Robert G. Wilson v_, Jan 03 2002

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Last modified July 11 01:51 EDT 2020. Contains 335600 sequences. (Running on oeis4.)