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

 

Logo

Thanks to everyone who made a donation during our annual appeal!
To see the list of donors, or make a donation, see the OEIS Foundation home page.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A066490 Number of primes of the form 4m+3 <= n. 5
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,7

COMMENTS

Partial sums of A079261. - Reinhard Zumkeller, Feb 06 2014

LINKS

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

MATHEMATICA

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

PROG

(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..]

-- Reinhard Zumkeller, Feb 06 2014

CROSSREFS

Cf. A066339.

Sequence in context: A000523 A124156 A072749 * A156685 A124230 A090973

Adjacent sequences:  A066487 A066488 A066489 * A066491 A066492 A066493

KEYWORD

easy,nonn

AUTHOR

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 January 16 15:31 EST 2019. Contains 319195 sequences. (Running on oeis4.)