The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 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: A124156 A324965 A072749 * A156685 A124230 A330780 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.

Last modified June 6 18:59 EDT 2020. Contains 334832 sequences. (Running on oeis4.)