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Search: id:A066339
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| A066339 |
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Number of primes p of the form 4m+1 with p <= n. |
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+0
4
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| 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 10, 10, 10, 10, 10, 10, 10, 10, 11, 11, 11
(list; graph; listen)
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OFFSET
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1,13
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COMMENT
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Asymptotic expansion: a(n) ~ pi(n)/2 ~ n/(2log(n)) (pi(n) is in sequence A000720).
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LINKS
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T. D. Noe, Table of n, a(n) for n=1..10000
R. Breusch, An Asymptotic Formula for Primes Of The Form 4n+1
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MATHEMATICA
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Table[ Length[ Select[ Union[ Table[ Prime[ PrimePi[i]], {i, 2, n}]], Mod[ #, 4] == 1 & ]], {n, 2, 100} ]
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PROGRAM
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(PARI) for(n=1, 200, print1(sum(i=1, n, if((i*isprime(i)-1)%4, 0, 1)), ", "))
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CROSSREFS
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Cf. A000720.
Sequence in context: A084558 A163291 A156875 this_sequence A052375 A074279 A072750
Adjacent sequences: A066336 A066337 A066338 this_sequence A066340 A066341 A066342
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KEYWORD
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nonn
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AUTHOR
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Sharon Sela (sharonsela(AT)hotmail.com), Jan 01 2002
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EXTENSIONS
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More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 03 2002
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