login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A066339 Number of primes p of the form 4m+1 with p <= n. 6
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; refs; listen; history; text; internal format)
OFFSET

1,13

COMMENTS

Asymptotic expansion: a(n) ~ pi(n)/2 ~ n/(2log(n)) (pi(n) is in sequence A000720).

Partial sums of A079260. - Reinhard Zumkeller, Feb 06 2014

LINKS

T. D. Noe, Table of n, a(n) for n=1..10000

R. Breusch, An Asymptotic Formula for Primes Of The Form 4n+1

MATHEMATICA

Table[ Length[ Select[ Union[ Table[ Prime[ PrimePi[i]], {i, 2, n}]], Mod[ #, 4] == 1 & ]], {n, 2, 100} ]

PROG

(PARI) for(n=1, 200, print1(sum(i=1, n, if((i*isprime(i)-1)%4, 0, 1)), ", "))

(Haskell)

a066339 n = a066339_list !! (n-1)

a066339_list = scanl1 (+) $ map a079260 [1..]

-- Reinhard Zumkeller, Feb 06 2014

CROSSREFS

Cf. A000720.

Sequence in context: A320065 A163291 A156875 * A052375 A212625 A171626

Adjacent sequences:  A066336 A066337 A066338 * A066340 A066341 A066342

KEYWORD

nonn

AUTHOR

Sharon Sela (sharonsela(AT)hotmail.com), Jan 01 2002

EXTENSIONS

More terms from Robert G. Wilson v, Jan 03 2002

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 22 09:43 EST 2019. Contains 320390 sequences. (Running on oeis4.)