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A066490
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Number of primes of the form 4m+3 that are <= n.
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9
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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, 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, 10, 10, 10, 11, 11, 11, 11, 11, 11, 11, 11, 12, 12, 12, 12, 13, 13, 13, 13, 13, 13, 13, 13, 13
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OFFSET
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1,7
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COMMENTS
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LINKS
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FORMULA
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MATHEMATICA
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Table[ Length[ Select[ Union[ Table[ Prime[ PrimePi[i]], {i, 2, n}]], Mod[ #, 4] == 3 & ]], {n, 2, 100} ]
Accumulate[Table[If[PrimeQ[n]&&Mod[n, 4]==3, 1, 0], {n, 100}]] (* Harvey P. Dale, Mar 17 2021 *)
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PROG
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(PARI) for(n=1, 100, print1(sum(i=1, n, if((i*isprime(i)-3)%4, 0, 1)), ", "))
(Haskell)
a066490 n = a066490_list !! (n-1)
a066490_list = scanl1 (+) $ map a079261 [1..]
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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